Hey, did you ever find a solution to your problem? I started receiving the same problem yesterday, and followed the same instructions on the site, I had no luck.

Hello! I recently had a similar issue—in addition to port forwarding, you should also ensure that your UPnP (Universal Plug n Play) settings are not blocked and/or switch to a separate (or wired) connection, if you’re able to do so. [url=https://steamcommunity.com/sharedfiles/filedetails/?id=561836866]This guide[/url] might be able to lend a hand in checking your settings. Best of luck, Guardian!