[HELP] MHP3 Lobbie Problem

[AdamN]

Is this issue occurred after changing the router? That is strange.. have you tried enabling UPnP on your router instead of DMZ?

Is the other person you're trying to play with is someone you know and have played with before? because if it's a random person on the internet the issue could be on their end and not on your side.
Even if you can chat with them doesn't mean they have their ports forwarded, for example people who use 3G/4G/LTE mobile internet connection will have their ports blocked by their ISP most of the time.

Also, have you tried using the latest official dev build from here https://buildbot.orphis.net/ppsspp/ it have more multiplayer fixes than the stable 1.11.3 version

PS: you don't need to create multiple threads of the same issue in this forum