Unhandled Exception: Mono.Linker.ResolutionException: Can not resolve reference

Been trying to get NTP time over TCP on iOS for a full day now and i can't make it work.

The error im getting is the following, at build time:

Unhandled Exception: Mono.Linker.ResolutionException: Can not resolve reference: System.Void System.Security.SecurityException::.ctor(System.String)

My stripping build settings in Unity are Stripping Level: Use micro mscorlib, and Script Call opimization: Slow and Safe.

Just putting the following code in any of my scripts triggers the above issue:

 System.Net.Sockets.TcpClient clientSocket = new System.Net.Sockets.TcpClient();

I guess it's a missing symbol somewhere but i have tried Stripping Level: None and adding all the classes to link.xml. If i turn off stripping the error occurrs at runtime instead "Attempting to JIT compile with --aot-only".

This is driving me insane, how do i open a simple TCP connection from Unity?!