Please help! Do I need to move my TV box when I move my wifi router?

We need to move our wifi box to a central location so we can get better wifi throughout the house.  We have a set top box and use Roku.  Do we have to move the set top box to the same room as the router?  I don't think our set top box is wireless since it is currently wired with a splitter (installed by a technician).  The cable comes in from the basement, through the splitter then one cord runs to the router and the other runs to the set top box.  Can we just bring the cable from the basement into the set top box  then in the othe room hook the basement cable into the router?  I cannot get a hold of any Comcast people and the chat feature is totally useless. Please help.  We are working at home due to COVID and cannot get good signals.