As per the installation instructions and notes, you can not access the panel in that manner. It needs to be on its own sub domain (like panel.domain.com or panel.domain.com:port). You would need a different certificate. One that covers all sub domains (https://*.domain.com) or one for the panel login (https://panel.domain.com) and a separate one for your site (https://domain.com, https//www.domain.com).
It is not designed to function the way you are describing.
It is not designed to function the way you are describing.