Originally Posted by till
The main domain of a website is the domain that you enter in the "domain" field of the site. I'am not talking about a main domain of the server. So you can have as many domains and as many IP addresses as youlike on the server, this does not matter for this setup at all.
So all you have to do is to exchange the content of the "domain" field of this website with the content of the "domain" field of the alias domain.
I think I see what you're saying by "main site". I thought you were meaning the "main site" for the server. Are you suggesting that I make the alias the domain and the domain the alias?
That is also a great idea and would totally work in most cases.
In my case though there are a few catches so I can't swap the two.
It is a very long and boring story why, but in a nutshell, the sites are actually wildcard SSL subdomains (I make them sites because I don't like the subfolder approach ISPConfig uses for subdomains) which may have 0-n number of SSL aliases per subdomain and they are part of larger network.