Signed in to PSN but not connecting to multiplayer network?

Disclaimer: I have no idea what I'm doing. I followed some youtube tutorial on installing HEN and recently updated to the 4.92.1 HFW but this problem existed before the update.

I turn on the system, enable HEN, then load the game (GTA4) and join the multiplayer lobby but 70% of the time it will just be me and only me. Everything else looks and feels normal except for the fact that not a single other soul will join the game. I've tried returning to single player and going back in, restarting the game etc. but the only thing that works is rebooting the console entirely, and even then it only works half the time. After 2 or 3 system reboots, suddenly there's plenty of other players.

Any ideas on how to fix this?