Hi guys, got an 'interesting' problem for you.
I've been using TNet for a little while now, quite successfully. Recently I decided to use my 30-day pro trial for Unity, and upon that trial expiring, TNet appears to have fallen into an odd 2-minute lock-up timeout when trying to connect.
This lock-up does not occur if my project is built using a pro version of Unity, and does not occur within the editor.
I have created a trivial test-case:

attached it to an object in an otherwise blank scene.
I then add two debug lines to TNTcpProtocol.cs like so:

and then build said project like so:

finally, I wait the 2 minutes for the build to unfreeze and have the following to see:

I can provide the entire project (512kb compressed) upon request as well. (I won't just add it here as it contains the entire TNet source of course.)
Just in case it is at all relevant, I am running Windows 8.1. This has not changed in the time I have been using TNet but I don't know how sockets work anywhere near well enough to know if that's useful information.
Additionally, I was using version 1.9.1, the latest version (1.9.5c I believe) has not solved the problem either.
edit: one more piece of info; Unity v 4.5.0f6
Anyone have any ideas on how I can fix this?
Cheers!