I used to have a problem where I allways had 'Lost connection to Host' shortly after the game came out it was so bad I gave up didnt play it for a few months until they released a patch which solved the problem and it went away over night.
Alas now with the new patch its returned, I have not been able to connect to a single game allways getting 'Lost connection to host'
Any ideas? I have tried temporarily disabling firewalls etc and nothing!
Is this just Black Ops? Is your net connection otherwise stable?
I noticed after the last patch (1.08) I was getting an insane amount of lag at the start of every round. Tried a few things but ended up swapping out the router and that solved things (old router ca. 4 yrs old). There are however certain setups that hate Black Ops, for example, if you have an SPI firewall enabled and especially if you log events.
New patch 1.09 just seems to have sharpened everything right up for me again. Feels like COD4 and 5 ... at last.
You shouldn't have to, but open up
these ports.
Another possible fix is to delete ClientRegistry.blob located in main Steam install folder.
Another possible fix is to open up steam, go to your list of installed games, right-click on your Black Ops MP, properties, files and verify cache. After that, defrag.
Another possible fix is to find players folder which is located in steam/steamapps/common/call of duty black ops and delete the config_mp file. Not so much this IMO but it will default the game back to it's original state and auto-create a new file once you start the game. You would have to re-enter your custom config etc.
f I can think of anything else, I'll tell you.