Cannot sign-in with shared SSL and 1and1

[DrByte]

Unless they have changed it, managed servers are limited to one IP address, which I assume means one SSL certificate. I'm under the impression SSL certificates can't share an IP, but that's something upon which I have to do more research.

That has long been the case, mostly because of the way webservers handle SSL. There have been small steps forward in making Apache able to handle multiple SSL certs per IP address without having to use a shared wildcard address, but it's not yet widely adopted. But, your research might lead you down a path where you have the kind of control you need, especially if you're self-managing the server and can quickly tweak things where needed.