Are you forcing out Version 11 users?
I have a paid "perpetual" (or life-time) license for TV version 11.
It has worked well to connect to my clients with the QuickSupport agent for several years.
Lately however (perhaps 3 or 4 months?) it will not let me connect to many of my clients. Perhaps as many as 80% of my endpoints can no longer be contacted. They show up as online. They have not been upgraded to a newer version. They just give a mostly unhelpful error:
"A connection could not be established. Reason unknown."
There's a chance that it might cluster in my defined groups. That is, in the group "My Partners" I can connect to all the PCs. In the group "Small Offices" and "Joe's Motors" I can't connect to any.
I can't try every endpoint because I generally don't connect to my customer's PCs unless they call and ask me to. I can only try servers and security systems... things that should have nobody logged in at the desktop anyway.