We are remodeling our house so we fished coax and ethernet through the office, to TVs, and to strategic mesh hotspot areas.

When I hooked up my modem to the new coax in my office, the modem appeared to connect. However, my TPLink Deco (mesh network) wouldn't connect to the modem. I could hardwire my laptop into the modem and it worked. Confused, I spent a few hours, unplugging, resetting the Deco (never want to do that again), and finally giving up.

I told my electrician about it when he passed by a few days later and he cut off the coax tip and put a new one on. Lo and behold it worked. The Deco connected.

I'm still confused. His insight was that maybe the Deco was tracking the signal and the tip didn't have a clean connection.