Try getting ~10 years old uplay game to work and despair. Not sure what network engine they used at the time but there is an entire set of games that basically can't connect properly without using random ports anywhere in the 10k/60k range, it's ridiculous.

And let's not ever talk about two people in the same home playing the same game together. I loved splinter cell blacklist's multiplayer but damn did it take long to get anything connected.

I'm not even sure why I mean this was with internet gaming already being the norm, I assume it's because they made games for console and then ported, and on console port issue are handled for them or whatever ? Anyway this was stupid