I've recently reinstalled ISPConfig. I've found that I cannot login to the admin page by domain name, but I can by IP address. When I go to https://domainname.tld:8080, I get a login prompt. I provide my credentials, and the page is just reloaded without any error. When I go instead to https://188.8.131.52:8080, I get the same login prompt, and I'm able to successfully log in. Any ideas? I've verified it can resolve itself at the command line.