diff --git a/Assets/Mirror/Core/Tools/Compression.cs b/Assets/Mirror/Core/Tools/Compression.cs
index d04b566b1..f6bd06fa5 100644
--- a/Assets/Mirror/Core/Tools/Compression.cs
+++ b/Assets/Mirror/Core/Tools/Compression.cs
@@ -71,6 +71,24 @@ public static bool ScaleToLong(Vector3 value, float precision, out long x, out l
             return result;
         }
 
+        // returns
+        //   'true' if scaling was possible within 'long' bounds.
+        //   'false' if clamping was necessary.
+        //   never throws. checking result is optional.
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        public static bool ScaleToLong(Quaternion value, float precision, out long x, out long y, out long z, out long w)
+        {
+            // attempt to convert every component.
+            // do not return early if one conversion returned 'false'.
+            // the return value is optional. always attempt to convert all.
+            bool result = true;
+            result &= ScaleToLong(value.x, precision, out x);
+            result &= ScaleToLong(value.y, precision, out y);
+            result &= ScaleToLong(value.z, precision, out z);
+            result &= ScaleToLong(value.w, precision, out w);
+            return result;
+        }
+
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
         public static bool ScaleToLong(Vector3 value, float precision, out Vector3Long quantized)
         {
@@ -78,6 +96,13 @@ public static bool ScaleToLong(Vector3 value, float precision, out Vector3Long q
             return ScaleToLong(value, precision, out quantized.x, out quantized.y, out quantized.z);
         }
 
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        public static bool ScaleToLong(Quaternion value, float precision, out Vector4Long quantized)
+        {
+            quantized = Vector4Long.zero;
+            return ScaleToLong(value, precision, out quantized.x, out quantized.y, out quantized.z, out quantized.w);
+        }
+
         // multiple by precision.
         // for example, 0.1 cm precision converts '50' long to '5.0f' float.
         public static float ScaleToFloat(long value, float precision)
@@ -103,10 +128,25 @@ public static Vector3 ScaleToFloat(long x, long y, long z, float precision)
             return v;
         }
 
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        public static Quaternion ScaleToFloat(long x, long y, long z, long w, float precision)
+        {
+            Quaternion v;
+            v.x = ScaleToFloat(x, precision);
+            v.y = ScaleToFloat(y, precision);
+            v.z = ScaleToFloat(z, precision);
+            v.w = ScaleToFloat(w, precision);
+            return v;
+        }
+
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
         public static Vector3 ScaleToFloat(Vector3Long value, float precision) =>
             ScaleToFloat(value.x, value.y, value.z, precision);
 
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        public static Quaternion ScaleToFloat(Vector4Long value, float precision) =>
+            ScaleToFloat(value.x, value.y, value.z, value.w, precision);
+
         // scale a float within min/max range to an ushort between min/max range
         // note: can also use this for byte range from byte.MinValue to byte.MaxValue
         public static ushort ScaleFloatToUShort(float value, float minValue, float maxValue, ushort minTarget, ushort maxTarget)
diff --git a/Assets/Mirror/Core/Tools/DeltaCompression.cs b/Assets/Mirror/Core/Tools/DeltaCompression.cs
index a59370a2b..50b9b2f86 100644
--- a/Assets/Mirror/Core/Tools/DeltaCompression.cs
+++ b/Assets/Mirror/Core/Tools/DeltaCompression.cs
@@ -26,6 +26,16 @@ public static void Compress(NetworkWriter writer, Vector3Long last, Vector3Long
             Compress(writer, last.z, current.z);
         }
 
+        // delta (usually small), then zigzag varint to support +- changes
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        public static void Compress(NetworkWriter writer, Vector4Long last, Vector4Long current)
+        {
+            Compress(writer, last.x, current.x);
+            Compress(writer, last.y, current.y);
+            Compress(writer, last.z, current.z);
+            Compress(writer, last.w, current.w);
+        }
+
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
         public static Vector3Long Decompress(NetworkReader reader, Vector3Long last)
         {
@@ -34,5 +44,15 @@ public static Vector3Long Decompress(NetworkReader reader, Vector3Long last)
             long z = Decompress(reader, last.z);
             return new Vector3Long(x, y, z);
         }
+
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        public static Vector4Long Decompress(NetworkReader reader, Vector4Long last)
+        {
+            long x = Decompress(reader, last.x);
+            long y = Decompress(reader, last.y);
+            long z = Decompress(reader, last.z);
+            long w = Decompress(reader, last.w);
+            return new Vector4Long(x, y, z, w);
+        }
     }
 }
diff --git a/Assets/Mirror/Core/Tools/Vector4Long.cs b/Assets/Mirror/Core/Tools/Vector4Long.cs
new file mode 100644
index 000000000..0eba99a32
--- /dev/null
+++ b/Assets/Mirror/Core/Tools/Vector4Long.cs
@@ -0,0 +1,126 @@
+#pragma warning disable CS0659 // 'Vector4Long' overrides Object.Equals(object o) but does not override Object.GetHashCode()
+#pragma warning disable CS0661 // 'Vector4Long' defines operator == or operator != but does not override Object.GetHashCode()
+
+// Vector4Long by mischa (based on game engine project)
+using System;
+using System.Runtime.CompilerServices;
+
+namespace Mirror
+{
+    public struct Vector4Long
+    {
+        public long x;
+        public long y;
+        public long z;
+        public long w;
+
+        public static readonly Vector4Long zero = new Vector4Long(0, 0, 0, 0);
+        public static readonly Vector4Long one = new Vector4Long(1, 1, 1, 1);
+
+        // constructor /////////////////////////////////////////////////////////
+        public Vector4Long(long x, long y, long z, long w)
+        {
+            this.x = x;
+            this.y = y;
+            this.z = z;
+            this.w = w;
+        }
+
+        // operators ///////////////////////////////////////////////////////////
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        public static Vector4Long operator +(Vector4Long a, Vector4Long b) =>
+            new Vector4Long(a.x + b.x, a.y + b.y, a.z + b.z, a.w + b.w);
+
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        public static Vector4Long operator -(Vector4Long a, Vector4Long b) =>
+            new Vector4Long(a.x - b.x, a.y - b.y, a.z - b.z, a.w - b.w);
+
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        public static Vector4Long operator -(Vector4Long v) =>
+            new Vector4Long(-v.x, -v.y, -v.z, -v.w);
+
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        public static Vector4Long operator *(Vector4Long a, long n) =>
+            new Vector4Long(a.x * n, a.y * n, a.z * n, a.w * n);
+
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        public static Vector4Long operator *(long n, Vector4Long a) =>
+            new Vector4Long(a.x * n, a.y * n, a.z * n, a.w * n);
+
+        // == returns true if approximately equal (with epsilon).
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        public static bool operator ==(Vector4Long a, Vector4Long b) =>
+            a.x == b.x &&
+            a.y == b.y &&
+            a.z == b.z &&
+            a.w == b.w;
+
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        public static bool operator !=(Vector4Long a, Vector4Long b) => !(a == b);
+
+        // NO IMPLICIT System.Numerics.Vector4Long conversion because double<->float
+        // would silently lose precision in large worlds.
+
+        // [i] component index. useful for iterating all components etc.
+        public long this[int index]
+        {
+            [MethodImpl(MethodImplOptions.AggressiveInlining)]
+            get
+            {
+                switch (index)
+                {
+                    case 0: return x;
+                    case 1: return y;
+                    case 2: return z;
+                    case 3: return w;
+                    default: throw new IndexOutOfRangeException($"Vector4Long[{index}] out of range.");
+                }
+            }
+            [MethodImpl(MethodImplOptions.AggressiveInlining)]
+            set
+            {
+                switch (index)
+                {
+                    case 0:
+                        x = value;
+                        break;
+                    case 1:
+                        y = value;
+                        break;
+                    case 2:
+                        z = value;
+                        break;
+                    case 3:
+                        w = value;
+                        break;
+                    default: throw new IndexOutOfRangeException($"Vector4Long[{index}] out of range.");
+                }
+            }
+        }
+
+        // instance functions //////////////////////////////////////////////////
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        public override string ToString() => $"({x} {y} {z} {w})";
+
+        // equality ////////////////////////////////////////////////////////////
+        // implement Equals & HashCode explicitly for performance.
+        // calling .Equals (instead of "==") checks for exact equality.
+        // (API compatibility)
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        public bool Equals(Vector4Long other) =>
+            x == other.x && y == other.y && z == other.z && w == other.w;
+
+        // Equals(object) can reuse Equals(Vector4)
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        public override bool Equals(object other) =>
+            other is Vector4Long vector4 && Equals(vector4);
+
+#if UNITY_2021_3_OR_NEWER
+        // Unity 2019/2020 don't have HashCode.Combine yet.
+        // this is only to avoid reflection. without defining, it works too.
+        // default generated by rider
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        public override int GetHashCode() => HashCode.Combine(x, y, z, w);
+#endif
+    }
+}
diff --git a/Assets/Mirror/Core/Tools/Vector4Long.cs.meta b/Assets/Mirror/Core/Tools/Vector4Long.cs.meta
new file mode 100644
index 000000000..7d5ede1cf
--- /dev/null
+++ b/Assets/Mirror/Core/Tools/Vector4Long.cs.meta
@@ -0,0 +1,3 @@
+fileFormatVersion: 2
+guid: 9f69bf6b6d73476ab3f31dd635bb6497
+timeCreated: 1726777293
\ No newline at end of file
diff --git a/Assets/Mirror/Tests/Editor/Tools/CompressionTests.cs b/Assets/Mirror/Tests/Editor/Tools/CompressionTests.cs
index 617902503..06f609f06 100644
--- a/Assets/Mirror/Tests/Editor/Tools/CompressionTests.cs
+++ b/Assets/Mirror/Tests/Editor/Tools/CompressionTests.cs
@@ -86,6 +86,32 @@ public void ScaleToLong_Vector3_OutOfRange()
             Assert.That(z, Is.EqualTo(long.MinValue));
         }
 
+        [Test]
+        public void ScaleToLong_Quaternion()
+        {
+            // 0, positive, negative
+            Assert.True(Compression.ScaleToLong(new Quaternion(0, 10.5f, -100.5f, -10.5f), 0.1f, out long x, out long y, out long z, out long w));
+            Assert.That(x, Is.EqualTo(0));
+            Assert.That(y, Is.EqualTo(105));
+            Assert.That(z, Is.EqualTo(-1005));
+            Assert.That(w, Is.EqualTo(-105));
+        }
+
+        [Test]
+        public void ScaleToLong_Quaternion_OutOfRange()
+        {
+            float precision = 0.1f;
+            float largest = long.MaxValue / 0.1f;
+            float smallest = long.MinValue / 0.1f;
+
+            // 0, largest, smallest
+            Assert.False(Compression.ScaleToLong(new Quaternion(0, largest, smallest, 0), precision, out long x, out long y, out long z, out long w));
+            Assert.That(x, Is.EqualTo(0));
+            Assert.That(y, Is.EqualTo(long.MaxValue));
+            Assert.That(z, Is.EqualTo(long.MinValue));
+            Assert.That(w, Is.EqualTo(0));
+        }
+
         [Test]
         public void ScaleToFloat()
         {
@@ -130,6 +156,17 @@ public void ScaleToFloat_Vector3()
             Assert.That(v.z, Is.EqualTo(-100.5f));
         }
 
+        [Test]
+        public void ScaleToFloat_Quaternion()
+        {
+            // 0, positive, negative
+            Quaternion q = Compression.ScaleToFloat(0, 105, -1005, -105, 0.1f);
+            Assert.That(q.x, Is.EqualTo(0));
+            Assert.That(q.y, Is.EqualTo(10.5f));
+            Assert.That(q.z, Is.EqualTo(-100.5f));
+            Assert.That(q.w, Is.EqualTo(-10.5f));
+        }
+
         [Test]
         public void LargestAbsoluteComponentIndex()
         {
diff --git a/Assets/Mirror/Tests/Editor/Tools/DeltaCompressionTests.cs b/Assets/Mirror/Tests/Editor/Tools/DeltaCompressionTests.cs
index 7d3c3abed..1d60129e7 100644
--- a/Assets/Mirror/Tests/Editor/Tools/DeltaCompressionTests.cs
+++ b/Assets/Mirror/Tests/Editor/Tools/DeltaCompressionTests.cs
@@ -59,7 +59,7 @@ public void Compress_Long_Changed_Large()
 
             // two components = 8 bytes changed.
             // delta should compress it down a lot.
-            // 7000 delta should use a few more bytse.
+            // 7000 delta should use a few more bytes.
             Assert.That(writer.Position, Is.EqualTo(3));
 
             // decompress should get original result
@@ -123,7 +123,7 @@ public void Compress_Vector3Long_YZChanged_Large()
 
             // two components = 8 bytes changed.
             // delta should compress it down a lot.
-            // 7000 delta should use a few more bytse.
+            // 7000 delta should use a few more bytes.
             Assert.That(writer.Position, Is.EqualTo(5));
 
             // decompress should get original result
@@ -131,5 +131,69 @@ public void Compress_Vector3Long_YZChanged_Large()
             Vector3Long decompressed = DeltaCompression.Decompress(reader, last);
             Assert.That(decompressed, Is.EqualTo(current));
         }
+
+        [Test]
+        public void Compress_Vector4Long_Unchanged()
+        {
+            NetworkWriter writer = new NetworkWriter();
+
+            Vector4Long last    = new Vector4Long(1, 2, 3, 4);
+            Vector4Long current = new Vector4Long(1, 2, 3, 4); // unchanged
+
+            // delta compress current against last
+            DeltaCompression.Compress(writer, last, current);
+
+            // nothing changed.
+            // delta should compress it down a lot.
+            Assert.That(writer.Position, Is.EqualTo(4));
+
+            // decompress should get original result
+            NetworkReader reader = new NetworkReader(writer);
+            Vector4Long decompressed = DeltaCompression.Decompress(reader, last);
+            Assert.That(decompressed, Is.EqualTo(current));
+        }
+
+        [Test]
+        public void Compress_Vector4Long_ZWChanged()
+        {
+            NetworkWriter writer = new NetworkWriter();
+
+            Vector4Long last    = new Vector4Long(1, 2, 3, 4);
+            Vector4Long current = new Vector4Long(1, 2, 7, 8); // only 2 components change
+
+            // delta compress current against last
+            DeltaCompression.Compress(writer, last, current);
+
+            // two components = 8 bytes changed.
+            // delta should compress it down a lot.
+            Assert.That(writer.Position, Is.EqualTo(4));
+
+            // decompress should get original result
+            NetworkReader reader = new NetworkReader(writer);
+            Vector4Long decompressed = DeltaCompression.Decompress(reader, last);
+            Assert.That(decompressed, Is.EqualTo(current));
+        }
+
+        [Test]
+        public void Compress_Vector4Long_ZWChanged_Large()
+        {
+            NetworkWriter writer = new NetworkWriter();
+
+            Vector4Long last    = new Vector4Long(1, 2, 3, 4);
+            Vector4Long current = new Vector4Long(1, 2, 5, 7000); // only 2 components change
+
+            // delta compress current against last
+            DeltaCompression.Compress(writer, last, current);
+
+            // two components = 8 bytes changed.
+            // delta should compress it down a lot.
+            // 7000 delta should use a few more bytes.
+            Assert.That(writer.Position, Is.EqualTo(6));
+
+            // decompress should get original result
+            NetworkReader reader = new NetworkReader(writer);
+            Vector4Long decompressed = DeltaCompression.Decompress(reader, last);
+            Assert.That(decompressed, Is.EqualTo(current));
+        }
     }
 }
diff --git a/Assets/Mirror/Tests/Editor/Tools/Vector4LongTests.cs b/Assets/Mirror/Tests/Editor/Tools/Vector4LongTests.cs
new file mode 100644
index 000000000..3c8e20cf6
--- /dev/null
+++ b/Assets/Mirror/Tests/Editor/Tools/Vector4LongTests.cs
@@ -0,0 +1,154 @@
+using System;
+using NUnit.Framework;
+
+namespace Mirror.Tests.Tools
+{
+    public class Vector4LongTests
+    {
+        [Test]
+        public void Constructor()
+        {
+            Vector4Long v = new Vector4Long();
+            Assert.That(v.x, Is.EqualTo(0));
+            Assert.That(v.y, Is.EqualTo(0));
+            Assert.That(v.z, Is.EqualTo(0));
+            Assert.That(v.w, Is.EqualTo(0));
+        }
+
+        [Test]
+        public void ConstructorXYZ()
+        {
+            Vector4Long v = new Vector4Long(1, 2, 3, 4);
+            Assert.That(v.x, Is.EqualTo(1));
+            Assert.That(v.y, Is.EqualTo(2));
+            Assert.That(v.z, Is.EqualTo(3));
+            Assert.That(v.w, Is.EqualTo(4));
+        }
+
+        [Test]
+        public void OperatorAdd()
+        {
+            Vector4Long a = new Vector4Long(1, 2, 3, 4);
+            Vector4Long b = new Vector4Long(2, 3, 4, 5);
+            Assert.That(a + b, Is.EqualTo(new Vector4Long(3, 5, 7, 9)));
+        }
+
+        [Test]
+        public void OperatorSubtract()
+        {
+            Vector4Long a = new Vector4Long(1, 2, 3, 4);
+            Vector4Long b = new Vector4Long(-2, -3, -4, -5);
+            Assert.That(a - b, Is.EqualTo(new Vector4Long(3, 5, 7, 9)));
+        }
+
+        [Test]
+        public void OperatorInverse()
+        {
+            Vector4Long v = new Vector4Long(1, 2, 3, 4);
+            Assert.That(-v, Is.EqualTo(new Vector4Long(-1, -2, -3, -4)));
+        }
+
+        [Test]
+        public void OperatorMultiply()
+        {
+            Vector4Long a = new Vector4Long(1, 2, 3, 4);
+            // a * n, n * a are two different operators. test both.
+            Assert.That(a * 2, Is.EqualTo(new Vector4Long(2, 4, 6, 8)));
+            Assert.That(2 * a, Is.EqualTo(new Vector4Long(2, 4, 6, 8)));
+        }
+
+#if UNITY_2021_3_OR_NEWER
+        [Test]
+        public void OperatorEquals()
+        {
+            // two vectors which are approximately the same
+            Vector4Long a = new Vector4Long(1, 2, 3, 4);
+            Vector4Long b = new Vector4Long(1, 2, 3, 4);
+            Assert.That(a == b, Is.True);
+
+            // two vectors which are definitely not the same
+            Assert.That(a == Vector4Long.one, Is.False);
+        }
+
+        [Test]
+        public void OperatorNotEquals()
+        {
+            // two vectors which are approximately the same
+            Vector4Long a = new Vector4Long(1, 2, 3, 4);
+            Vector4Long b = new Vector4Long(1, 2, 3, 4);
+            Assert.That(a != b, Is.False);
+
+            // two vectors which are definitely not the same
+            Assert.That(a != Vector4Long.one, Is.True);
+        }
+#endif
+
+        [Test]
+        public void OperatorIndexer()
+        {
+            Vector4Long a = new Vector4Long(1, 2, 3, 4);
+
+            // get
+            Assert.That(a[0], Is.EqualTo(1));
+            Assert.That(a[1], Is.EqualTo(2));
+            Assert.That(a[2], Is.EqualTo(3));
+            Assert.That(a[3], Is.EqualTo(4));
+            Assert.Throws<IndexOutOfRangeException>(() =>
+            {
+                double _ = a[-1];
+            });
+            Assert.Throws<IndexOutOfRangeException>(() =>
+            {
+                double _ = a[4];
+            });
+
+            // set
+            a[0] = -1;
+            a[1] = -2;
+            a[2] = -3;
+            a[3] = -4;
+            Assert.Throws<IndexOutOfRangeException>(() => { a[-1] = 0; });
+            Assert.Throws<IndexOutOfRangeException>(() => { a[4] = 0; });
+            Assert.That(a, Is.EqualTo(new Vector4Long(-1, -2, -3, -4)));
+        }
+
+        [Test]
+        public void ToStringTest()
+        {
+            // should be rounded to :F2
+            Vector4Long v = new Vector4Long(-10, 0, 42, 3);
+            Assert.That(v.ToString(), Is.EqualTo("(-10 0 42 3)"));
+        }
+
+#if UNITY_2021_3_OR_NEWER
+        [Test]
+        public void EqualsVector4Long()
+        {
+            Assert.That(Vector4Long.one.Equals(Vector4Long.one), Is.True);
+            Assert.That(Vector4Long.one.Equals(Vector4Long.zero), Is.False);
+        }
+
+        [Test]
+        public void EqualsObject()
+        {
+            Assert.That(Vector4Long.one.Equals((object)42), Is.False);
+            Assert.That(Vector4Long.one.Equals((object)Vector4Long.one), Is.True);
+            Assert.That(Vector4Long.one.Equals((object)Vector4Long.zero), Is.False);
+        }
+
+        [Test]
+        public void GetHashCodeTest()
+        {
+            // shouldn't be 0
+            Assert.That(Vector4Long.zero.GetHashCode(), !Is.EqualTo(0));
+            Assert.That(Vector4Long.one.GetHashCode(), !Is.EqualTo(0));
+
+            // should be same for same vector
+            Assert.That(Vector4Long.zero.GetHashCode(), Is.EqualTo(Vector4Long.zero.GetHashCode()));
+
+            // should be different for different vectors
+            Assert.That(Vector4Long.zero.GetHashCode(), !Is.EqualTo(Vector4Long.one.GetHashCode()));
+        }
+#endif
+    }
+}
diff --git a/Assets/Mirror/Tests/Editor/Tools/Vector4LongTests.cs.meta b/Assets/Mirror/Tests/Editor/Tools/Vector4LongTests.cs.meta
new file mode 100644
index 000000000..b77712d45
--- /dev/null
+++ b/Assets/Mirror/Tests/Editor/Tools/Vector4LongTests.cs.meta
@@ -0,0 +1,3 @@
+fileFormatVersion: 2
+guid: a966f5fd1b865460abc471e46bcee889
+timeCreated: 1666897728
\ No newline at end of file