Play PSP ad-hoc games over ZeroTier with PPSSPP

ZeroTier creates a virtual LAN so PPSSPP clients in different places can use PPSSPP's built-in ad-hoc server, as described in PPSSPP's LAN/VPN guide. This is for PPSSPP. It is not a documented way to put a real PSP onto ZeroTier.

Set up ZeroTier

1. Create an account and a network at my.zerotier.com. Copy the 16-character Network ID.
2. Install ZeroTier on every device from the official download page.
3. Join the same Network ID on every device.
4. In the ZeroTier Central dashboard, authorize each member if the network is private.
5. Note the host's ZeroTier-assigned IP from the dashboard or the ZeroTier client. That is the address other players will enter in PPSSPP.

Configure PPSSPP

These steps follow PPSSPP's LAN/VPN ad-hoc instructions. Use the same PPSSPP version on every device when you can.

1. Open Settings > Networking and enable Enable Networking/WLAN.
2. Disable Try to use server-provided packet relay on every player.
3. Disable Enable UPnP on every player (you do not need port forwarding on a virtual LAN).
4. Set Port offset to the same value on every player. If you are unsure, use 10000.
5. On the host only: open the PRO ad-hoc server address option, use Toggle List to find your VPN IP (not your normal LAN IP), and enable Enable built-in PRO ad hoc server. Then start the game and host or wait in the lobby until you see "Network Initialized".
6. On everyone else: set the PRO ad-hoc server address to the host's VPN IP, keep the built-in ad-hoc server disabled, and join the host's game. Do not type leading zeros in the IP (use 192.168.1.1, not 192.168.001.001).

Do not use localhost as the server address when players are on different devices.

Source for the PPSSPP steps: How to play multiplayer games with PPSSPP.