Play PSP ad-hoc games on PSP Relay with PPSSPP

PSP Relay uses public aemu_postoffice relays so PPSSPP can play ad-hoc games over the internet with other PPSSPP clients, real PSPs, and PS Vitas, without port forwarding. This needs PPSSPP 1.20.1 or later.

Setup

1. Open Settings > Networking and enable networking (the Wi-Fi icon in portrait mode).
2. Under Ad Hoc multiplayer, set a Nickname. For ad-hoc this is the same as the emulated PSP's system nickname.
3. Choose a server from the list in the app, or browse the ad-hoc server list. Well-known relays include socom.cc, psp.mgn.pub, eahub.eu, and psi-hate.com.
4. Leave Try to use server-provided packet relay on Auto unless you know you need to force it. Auto uses the relay when the selected server supports it.
5. Set Port offset to 10000 unless your group has already agreed on another value. Everyone must use the same offset, including real PSP and Vita players (they set it in aemu's port_offset.txt).
6. On every device, choose the same server, then create or join an ad-hoc room in the game as usual.

Notes

• Use PPSSPP 1.20.1 or later so relay mode works as documented.
• Do not enable the built-in PRO ad-hoc server while you are using a public relay.
• If you ever add a custom server by IP for a local or P2P session, uncheck Relay server mode when you add it, as described in the quickstart.

Sources: PPSSPP multiplayer quickstart, ad-hoc server list, how to play.