Upnp problem

[AdamN]

"Data from unknown port [PPSSPP]" means that the sender (ie. you) is using a different port than what's supposed to be.
This can happen if the router or ISP is remapping the port (not sure what was the reason, may be the port were already used by someone else, in the case if it was shared public IP).

You can try using a different port offset value (try increasing it by 2000 or more), and hopefully the router/ISP can accept the port as-is without remapping it.

Btw, i hope you're not playing with another Player on the same network over the internet, because both of you will share the same public IP, thus it won't work.