If you get this error when trying to connect to your Home Server using Windows Home Server Console, welcome to the club.
When Googling you’ll find all kinds of advices to reinstall Connector software or even whole server. Luckily, all of those are wrong.
It turns out that all other components, like shared folder and backup connect to server using NETBIOS, but Console is using DNS resolution.
Sometimes (!) that resolves to server.your-isp.net or similar.
Solution? Stick servers IP in hosts, and restart!