I’ve spent days finding this solution so here is the result – thanks to this thread!!
How to Setup WHM and CPANL so clients will be redirected to a valid SSL Certificate when logging in.
Instructions based on WHM v11.15.0
1) Purchase / Install the Certificate for your fully qualified domain (ie: server.domain.com)
SSL / TLS >> Install a SSL Certificate and Setup the Domain
2) Test your new CERT
should resolve and the cert should function properly before moving forward.
should be giving you an invalid certificate error
3) Install the CERT for the WHM and CPANEL Service (this is the step you don’t think about!!)
Service Configuration >> Manage Service SSL Certificates
> Select “Install New Certificate” for the “cPanel/WHM/Webmail Service”
> Select Domain this CRT is for “Browse”
> Pick the full server cert you installed “server.domain.com”
> Press “Submit” to install
4) Test your Service Certificate
should now be working !! WHOOOO
** Once your done, you may choose to install the same cert for your SMTP, POP, and FTP accounts so that the option is available and functioning properly
Error with SSL and Port 2087
Error with SSL and Port 2083
Error with WHM SSL
Error with CPANEL SSL