I used the Letsencrypt option in Webmin Configuration to issue a new cert directly for Webmin since copying from the main domain does not work (copies to Usermin only no matter if I choose Webmin or Usermin as the target in the Virtual Server settings).
A new cert was issues and before saving I did double check there was now a new path to the Webmin cert under /etc/webmin/letsencrypt-key.pem
Unfortunately I get SSL_ERROR_RX_RECORD_TOO_LONG in Firefox and can't login via https. Must edit miniserv.conf with ssl=0 to get back into Webmin.
Tried to issue an new self-signed cert to see if I can restore things but to no prevail. What am I doing wrong?