minecraft-pi-reborn/docs/MULTIPLAYER.md

Multiplayer

MCPI-Reborn supports two ways to play multiplayer.

Local Network (LAN)

This is also supported by vanilla MCPI. Just load a world in MCPI and other devices on the network can join.

External Servers

Unlike vanilla MCPI, MCPI-Reborn allows you to natively join a server outside of the local network. Just modify ~/.minecraft-pi/servers.txt (or ~/.var/app/com.thebrokenrail.MCPIReborn/.minecraft-pi/servers.txt if you are using the Flatpak) and it should show up in MCPI's server list.

Example ~/.minecraft-pi/servers.txt

# Default Port Is 19132
example.com
# Custom Port
example.com:19133