Comcast to DIRECTV back to Comcast

I am trying to do a self install back to Comcast. I’ve had my own modem box with Comcast for years installed in my home/office. The satellite came in through bedroom 2. I tried to install the Tv box in the family room it doesn’t work. The only room it works is in the office as through a splitter it’s coming in directly. I seem to recall the installer for DIRECTV indicated a splitter was installed in the attic. Do I need to remove and get a new splitter that connects the cables within the house and ignore the dish? Also is there a difference between white cables with blue strip vs black strip? Thanks!!