The new duel plugin allows to connect Centaur boards to each other.
The plugin itself is quite simple and needs to be improved.
No takeback, no resume feature, no clocks, no detailed matching requests yet.
The plugin takes the Lichess username as game username, means that you need to run at least one time the Lichess module to set your username (no need to launch a Lichess Centaur game, just need to display the home page).
This version obviously uses an external server to connect the two boards (the same than the chat room).
When you start your board, the Centaur sometimes fails to connect that external server (needs to be investigated), in that case, you just need to restart the WEB service from the web UI (system/restart WEB service).
(if you are not able to send messages using the web chat room, means that you are not connected to that external server...)
The new duel plugin allows to connect Centaur boards to each other.