Reproduction steps:
1) Download and open user's attached project
2) Make sure that Android is selected as Platform
3) Make sure that Scripting Backend is set to IL2CPP
4) Build and run this project on any Android device
5) Using ADB check output and notice:
ArgumentException: Type 'CTcpPacket' cannot be marshaled as an unmanaged structure; no meaningful size or offset can be computed.

Expected results:
Application built with IL2CPP scripting backend should be working same as Mono2x (should not throw ArgumentException)

Actual results:
ArgumentException is being thrown.

Reproduced with: 5.6.0a3, 5.5.0f2, 5.4.3f1, 5.3.7p2