How to reproduce:
1. Open given "Client" and "Server" unity projects
2. Enter "ClientTest" and "ServerTest" scenes
3. Set up IP and Port for both Client (127.0.0.1) and Server (127.0.0.1) through their respective objects in the test scene.
4. Enter Play Mode in the Server project and then in the Client project
5. Toggle the "Spam Messages" option to true in the Client's UI (WARNING: This may cause the Client to hang and will severely limit framerate)
6. Wait a few seconds until the Client hangs and the "Time Since Last Received Message" rises to a few seconds.
7. Disable the "Spam Messages" option (this may be difficult with the low framerate)
8. The Client will no longer receive any messages, even after the server has properly received all of the spam messages.

Expected result: Server should receive messages after it hangs
Actual result: Server stops receiving messages after hang

Regression first introduced in: 2017.2.0b2
Reproducible with: 2018.2.0b2, 2018.1.0f1, 2017.4.1f1, 2017.3.2f1, 2017.2.2p2,
Not reproducible with: 2017.1.3p2