I host an OC on a small home Nginx server, HTTPS is handled with a Let's Encrypt SSL certificate and the server is accessible from internet with no problem. When accessed from my router's LAN, things are different: network-wise, the host is accessible (e.g. I can SSH onto it), but the HTTPS server gives a "Échec de la connexion sécurisée" (Failure of secure connection) message. I guess there's something with Nginx or with the SSL certificate, but... what?
Any clue/idea would be great, thanks in advance!