"Connection failed after 4 retries" on every server and game, even though others can join.

[Samuka97]

Well so today Steam started effin' up, again. Now for every server on every single multiplayer game I own I get the message "Connection failed after 4 retries.". My friends can join just fine - but I can't connect. I can right click to see the IP and who's playing and I bet I could even ping the IP, but I can't join.

I've tried restarting my computer, router, doing ipconfig /release then /renew *, deleting clientregistry.blob, turning off my antivirus, completely killing all its processes etc etc but nothing so far worked. I've been searching and everybody has had this before, but only in specific servers in specific games. I get this for every game I own on every server that is online. It works for everyone else except for me.

I played some Sven Coop on a listen server I made and Portal 2 Co-Op yesterday with my friend, so I can say for sure it was okay before and this is a new problem. I've pretty much ran out of things to do and it still doesn't work. What the hell is this about?

[lahey]

Tried disabling your firewall?