
Checked Hijackthis for any malware or suspicious entries (=> some changes made no effect) Checked the "hosts" file for any funny business, as far as I could tell (=>no change made, no change occurred) Tried deleting single files from the Steam folder (instead of the entire folder) and restart (=> updated instantly, no change) Tried to connect to Steam through another VPN (=> nope)
#Tera playonmac update
Rolled back ANY Windows update that I could possibly roll back (=> no change repatched) Re-activated Windows Firewall and explicitly allowed any Steam-exe's. Re-Edited Portforwarding and Portriggering on my router (ASUS RT-N66U) (=> no change) Tried out different DNS-Servers(eg OpenDNS) on my wireless connection settings (instead of auto) (=> nothing) Connected to the router via another WirelessLAN stick (=> didn't change anything)
#Tera playonmac drivers
Tried to connect to Steam in safe mode with network drivers (=> didn't change it a bit) Tried to connect to Steam on the "Administrator" account (=> didn't do anything) Set Steam.exe entire folder to "trusted file(s)" in Comodo (=> didn't change anything) Portforwarded all necessary ports for steam (=> didn't change anything) Deactivated my Comodo Firewall and Avira AntiVir (=> didn't change anything) Used HotSpotShield to circumvent the problem (VPN to connect) (=> didn't change anything) Tried WinFixIt (or something like that) - updated again via Windows Update (=> didn't do anything) Don't have the possibility to run wired instead of wireless, so. Tried to fix the registry entries, concerning offline mode (=> already set to 0 didn't change anything) Since I didn't have a system restore point. Copying the Steam folder (except SteamApps) from another PC (which could connect just fine) (=> didn't fix it) Again, reinstalling Steam at this point (=> didn't fix it) Updating WLAN drivers manually (=> didn't fix it, rolled it back )
#Tera playonmac install
checked steampowered's list for possibly interfering programs that I might have installed (=> deleted a few, but didn't expect the problem to change, since I didn't install anything around the time, when the problem first occurred) (see above): Updated via Windows Update (=>125 updates and several reboots later, the problem still occurs) Checked update history (WLAN drivers?) (=> not updated - in fact, I had Windows Update turned OFF, the entire time) De-installing Steam, rebooting PC, reinstalling Steam (=> Updated fine, but error messages keep popping up)

Deleting all files in the Steam folder, but Steam.exe + Backup of SteamApps (=> Updated fine, but error messages keep popping up) Resetting both internet connection and PC (=> Changed nothing) Logging in to (=> Yup, changed nothing, though) Checking if other PCs in the network can connect to Steam (=> Working like a charm)

PLEASE READ THROUGH THE ENTIRE THREAD, IF YOU HAPPEN TO ENCOUNTER A SIMILAR PROBLEM, I'M SURE SOME METHOD MENTIONED WILL WORK ON YOU :)

EDIT after the issue has been solved, now:
