Signal problem 771 moves from room to room

I have 3 std boxes in the house. The box in Room A started having 1 second video blackouts, occassionally getting a 771 message. I reset it numerous times, unplugged the input cable numerous times with no luck. So, I took out the box from Room B and put into Room A and it worked great. So, I took out the B box from Room A and put everything back to original configuration with Room A using box A, Box B in Room B, etc.

Now Room A is fine but the box in Room B is now doing what was happening in room A. The 2 boxes were 100% for sure NOT mixed up. They are clearly marked. After 45 minutes on the phone with DTV there is no solution.

How could it possibly move from room to room??? This started about 2 hours ago and the weather here is calm, humid but dry. All I can think of is connection issues on the splitter on the roof. Weird.

The boxes (at the time they were affected) would switch channels without prompting but that may have been certain transponders losing signal momentarily. NEvertheless, how could it move from one box to another one. All cabling goes from LNB to splitter, to boxes, no couplers anywhere.

Any suggestions? Thanks