alert bad certificate: SSL alert number 42

Setup:

Code:

https://www.howtoforge.com/perfect-server-debian-12-buster-apache-bind-dovecot-ispconfig-3-2/

Code:

https://www.howtoforge.com/securing-your-ispconfig-3-managed-mailserver-with-a-valid-lets-encrypt-certificate/

Problem:

Code:

dovecot: imap-login: Disconnected: Connection closed: SSL_accept() failed: error:0A000412:SSL routines::sslv3 alert bad certificate: SSL alert number 42 (no auth attempts in 0 secs): user=<>

.acme Cert Update broke it?
I have tried and tried nothing I try fixes the cert offered by the server.
I even tried 2 purge dovecot and then I tried to change server name just in case there is somekind of conflict.
Nothing works.
Thunderbird keeps complaining about the cert.

Should I just use ISPconfig setup script and start from scratch?

Current config:
server original name: mail.mattila.eu
server name now: s1.mattila.eu
postfix setup: mail.mattila.eu, mattila.eu, s1.mattila.eu, imap.mattila.eu, smtp.mattila.eu

Thunderbird finds email account on imap.mattila.eu but not it's SSL cert.
Currently Dovecot offers s1.mattila.eu as SSL cert not imap.mattila.eu

 

/etc/dovecot/dovecot.conf points to postfix symlinks that point to ispconfig certs.
dh.pem is dovecot original.

Code:

ssl_cert = </etc/postfix/smtpd.cert
#ref# /etc/postfix/smtpd.cert -> /usr/local/ispconfig/interface/ssl/ispserver.crt

ssl_key = </etc/postfix/smtpd.key
#ref# /etc/postfix/smtpd.cert -> /usr/local/ispconfig/interface/ssl/ispserver.key

ssl_dh = </etc/dovecot/dh.pem

 

Easy solution would be to change server name to imap.mattila.eu.
It's website alias for mail.mattila.eu.