SSMS connect server type is grayed out

Solution 1:

Server type ist grayed out if you want to start a new connection using the "Connect" button on the left. If you klick on the "cable-symbol" (Connect Object Explorer) you can chose the server type.

I think this is silly, no idea what the purpose is...

Regarding the "Class Not Registered" Error, I'm pretty sure your SSMS is "too new" for your Instance. Try the oldest on this List: Previous SSMS releases

Edit:

What I meant in the comment was the Management Studio, not the DB Instance. With 2012 (2008r2 maybe too) you had to install Management Tools as Feature. I've found an old 2012 install image and started it up to show you this printscreen: Read the Feature description and check if you have installed this feature.