The top right of the picture that goes into a 4 way split. The coax cables are the ones that you screw on with a pointy wire in the middle and typically black cabling.


If that 4 way cable goes into the gray box beneath it…. Then it would be the wire that is feeding that gray box…. Perhaps the one running down the way.


Best guess is to find the wire that “enters” the basement alone… If there is one. The rest of the wires are likely to run off together towards different rooms in your house.

Look for the longer that doesn’t appear to plugged in next to a lot of other cables.