A connection could not be established. Partner could not be contected at the given network address.

in the last month or so i can no longer connect my laptop  remotely to my onsite computer.  It only connects -only when I am on the same network which of course I don't need to do.  When I return to my onsite computer that I have been trying to connect to, it is on and teamviewer is running.  This started with Teamviewr 11 and continues after upgrading bothe devices to 12.  Ideas?  thank you