substring instead

Author: anna-git

tracer/src/Datadog.Trace/Headers/Ip/IpExtractor.cs

@@ -122,7 +122,8 @@ private static bool IsPrivateIp(IPAddress ipAddress)
 #if NET6_0_OR_GREATER
             return ipAddress.IsIPv6UniqueLocal;
 #else
-            var firstWord = ipAddress.ToString().Split([':'], StringSplitOptions.RemoveEmptyEntries)[0];
+            var ipAddressString = ipAddress.ToString();
+            var firstWord = ipAddressString.Substring(0, ipAddressString.IndexOf(":", StringComparison.InvariantCulture));
             // These days Unique Local Addresses (ULA) are used in place of Site Local. ULA has two variants:
             // fc00::/8 is not defined yet, but might be used in the future for internal-use addresses
             // fd00::/8 is in use and does not have to registered anywhere.