serialize SendPacketsAsync tests (#63888)

diff --git a/src/libraries/System.Net.Sockets/tests/FunctionalTests/SendPacketsAsync.cs b/src/libraries/System.Net.Sockets/tests/FunctionalTests/SendPacketsAsync.cs
index 65764b4..10ebc47 100644 (file)
--- a/src/libraries/System.Net.Sockets/tests/FunctionalTests/SendPacketsAsync.cs
+++ b/src/libraries/System.Net.Sockets/tests/FunctionalTests/SendPacketsAsync.cs
@@ -13,6 +13,7 @@ using Xunit.Abstractions;
 
 namespace System.Net.Sockets.Tests
 {
+    [Collection(nameof(NoParallelTests))]
     public class SendPacketsAsync
     {
         private readonly ITestOutputHelper _log;