Ethernet cable wiring help - computer gigs

I run credit cards on a Terminal. We just moved here to Denver. I can run cards in our master bedroom because the router is there. But I cannot run them in the office. So I'm looking for someone that can maybe help me get this going. If you look at the pictures, that's what I have. The previous owner also put a alarm system in that has cameras and what not. I'm not sure if they changed some wiring or? I plugged an ethernet cable from the cable box to the wall and then I tried plugging the credit card terminal in the office into the wall outlet. And it does not communicate with the router.