devtrackers.gg
I'm aware of this issue, but I really don't think it has to do with the update. There were no changes in the update which would have affected this, and people were reporting the issue before the update, too. Also, some people are saying it just starts working again, and wondering if there was a patch to fix something -- there was no patch. I think it has to do with the underlying matchmaking servers that are run by Steam & GOG. It could also just be that some people have firewall, antivirus, or other systems that are interfering with multiplayer, and there are more reports than usual right now because the update just came out and more people are playing the game than normal. I had this issue happen to me, as well, and I got it to work by closing the game, going invisible or signing off steam, then opening again, and possibly repeating a few times. Eventually it just worked.