I tried to host a dedicated server for TF2 last night and play on the same system. Although other people could connect to my server when I tried TF2 crashed and displayed the following message:
"Couldn’t allocate any hltv IP port"
TF2 would crash on any connection attempt to any server while I had a DS running in the background.
I know my firewall/router setup/port forwarding is fine and I've had no problems hosting servers for Zombie Panic, CSS, FoF, Synergy or DIPRIP.
I've browsed a few other forums and checked google. A few other people are experiencing the problem but I haven't seen a solution. I know I could just run a listen server but I'd prefer to work out a way to setup a dedicated one.