Issue with /cpanel or /whm or /webmail.
If you are facing an issue that says user cant access cpanel by https://domain.com/cpanel then please try doing following,
1) Login ot WHM and go to “Tweak Settings”
2) Uncheck following two options from “System”,
Always redirect users to the ssl/tls ports when visiting /cpanel, /webmail, etc.
When visiting /cpanel or /whm or /webmail with ssl redirect to the servers hostname (unless a custom certificate has been installed in Manage Service Certificates).
In order to access /cpanel or /whm or /webmail these two options should be unchecked.