Splitter advice needed

There is a splitter in my apt. Last night all power went down, TV and Internet. CASE is the error message on my box.
I’ve done all troubleshooting and it’s been decided this MUST have something to do with my wiring (APT). Neighbors all up and running. No outages locally.
Our cable was originally hooked up in the BR (daughters room) why not LR? No CLUE but a splitter was installed and wired and for two years it’s worked fine.
If suddenly it takes a dump what should I replace? There is a box the wires were hooked to. If that has a problem would that make everything take a dive or is it more than likely the wires? Splitter itself? Help! It’s Corona virus shelter in place and we got NOTHING.