many, MANY stories of spliters not being securely fastened OR some doofus stapled into the coax
My suggestion is to get a toner and test the lines... rerunning cable is not an easy proposition in some rv's ...
when one of my cables went bad, I got a 4 to 1
rocketfish switcher from best buy and hooked everything so it went down the 'good' cable
takes one more switch when I want to watch the blueray player, but that's not very often...
good luck !