I use MyVesta (Debian 11 of course), my domain has got a Let's Encrypt certificate (i modified nginx.conf to additionally enable TLS 1.3), generated by MyVesta.
When i trying to connect to mail server (to configure email account on phone) on phones with Android 9 and 11, i receiving an error "Can't connect to server, certificate is not valid or not trusted". But my certificate is valid in all online SSL checkers! BUT when i changed setting of SSL/TLS on phone to "accept all certificates", my phone connected to server on SSL without any problem.
Please help me with this.