Move Hub5

Hello. My Hub5 needs to be moved. Currently it is served from one side of a cable splitter, the other side serving a V6 box. I disconnected Hub & tried reconnecting downstairs with the cable used by the V6 box. However, although the Hub’s digital telephone connection was fine, I failed to achieve any WiFi. 
I believed the single cable into the house had all the necessary info., each device sorting the relevant required signal, with each side of the spitter being identical. I understand signal splitting can create problems but that has not been the case in the present set-up. I’m keen to avoid carpet & floorboard removal for more rewiring if at all possible.
Any advice/thoughts would be gratefully received. Thanks, D.