It's fiber up tot he point where it's converted to coax,
That last "mile" can cause a lot of problems though. Ingress, back feed, congestion. That is why Cox is investing so much into fiber, whether it be to support more nodes closer to the customer or actual FTTH. I am not anti Cox, I am just Pro Fiber. 🙂
their fiber system is old
I am sorry for your family members. My area was upgraded years ago and all that was needed was a new(free) ONT. I guess OP could tell what type of service is being used in the area by looking at the speeds listed for FIOS on the FCC Broadband Maps.