Fail to install and configure Nextcloud Signaling + Coturn

It seems that many people are having this problem with the CoTurn configuration: The server returned an error with code=701: STUN/TURN allocate request timed out. · Issue #678 · coturn/coturn · GitHub
But even reading their solution, i can’t manage to make Coturn working….

And i’m not the only one lost on this problem on this forum:

Anyone succeed to configure CoTurn?