System.Net.NetworkException : The operation is not allowed on non-connected sockets.
   at System.Net.Sockets.NetworkStream..ctor(Socket socket, FileAccess access, Boolean ownsSocket) in /_/src/libraries/System.Net.Sockets/src/System/Net/Sockets/NetworkStream.cs:line 81
   at System.Net.Sockets.NetworkStream..ctor(Socket socket, Boolean ownsSocket) in /_/src/libraries/System.Net.Sockets/src/System/Net/Sockets/NetworkStream.cs:line 32
   at System.Net.Test.Common.LoopbackServer.EstablishConnectionAsync() in /_/src/libraries/Common/tests/System/Net/Http/LoopbackServer.cs:line 115
   at System.Net.Test.Common.LoopbackServer.AcceptConnectionAsync(Func`2 funcAsync) in /_/src/libraries/Common/tests/System/Net/Http/LoopbackServer.cs:line 121
   at System.Threading.Tasks.TaskTimeoutExtensions.WhenAllOrAnyFailed(Task[] tasks) in /_/src/libraries/Common/tests/System/Threading/Tasks/TaskTimeoutExtensions.cs:line 96
   at System.Threading.Tasks.TaskTimeoutExtensions.WhenAllOrAnyFailed(Task[] tasks) in /_/src/libraries/Common/tests/System/Threading/Tasks/TaskTimeoutExtensions.cs:line 124
   at System.Net.Test.Common.LoopbackServer.<>c__DisplayClass13_0.<<CreateClientAndServerAsync>b__0>d.MoveNext() in /_/src/libraries/Common/tests/System/Net/Http/LoopbackServer.cs:line 87
--- End of stack trace from previous location ---
   at System.Net.Test.Common.LoopbackServer.CreateServerAsync(Func`2 funcAsync, Options options) in /_/src/libraries/Common/tests/System/Net/Http/LoopbackServer.cs:line 71
   at System.Net.WebSockets.Client.Tests.ConnectTest.ConnectAsync_CancellationRequestedAfterConnect_ThrowsOperationCanceledException() in /_/src/libraries/System.Net.WebSockets.Client/tests/ConnectTest.cs:line 264
--- End of stack trace from previous location ---