Digital converter for downstairs TV has always worked great, but the
one upstairs worked sporadically. It would often fail to "grab" the
digital signals. Get a different model for upstairs = same problem.
TV guy replaced the splitter which is physically located downstairs.
As soon as he left ... same problem.
To make a long story short ....
If the plug that powers the downstairs TV and converter is pulled from
the wall socket, the TV upstairs works sporadically.
If the upstairs plug is pulled from the wall socket, no problem. The
TV downstairs continues to work.
If both plugs are in the wall, upstairs TV works great.
SOLUTION: If you want to watch the TV upstairs, make sure that the
power plug downstairs is not unconnected. Keep it in the wall socket.
Wish someone would 'splain why.