My whole site uses https. However when I use the :8080 port to get to ISPConfig3 it says there is not https access and that it is unsecure.
8080 port should be access via https://yourserverdomain:8080 not https://yourwebsitedomain:8080. The warning was shown as the certificate belongs to yourserverdomain not your websitedomain. Otherwise you might want to check whether yourserver port 8080 is secured when you were installing ISPConfig at the first place. If not, do an update to your ISPConfig and choose SSL. You may also want to read or follow this guide
