Server problems

Whenever I host a listen server, it runs for about 2 minutes until it just goes into a loading screen and takes me back to the main menu. A friend and I are using Hamachi, and he can connect perfectly. I don't see what the problem is, this has always been a problem for me. Any help?

What if your friend hosts and you join? Sometimes it works if you just switch.

Still doesn't work. It ends in minutes for him, too.

happened to me a few months ago and i gave up trying.

i thought listen servers not working was a tf2 thing but apparently it's not that uncommon?

Hmm, sorry, no idea. I can't forward ports on my connection so I never looked into it really.