Fiber is always going to be superior then cable. I can understand you not wanting Cox but don't suggest to people to downgrade to cable/HFC. That's like saying Ford makes bad combustion engines so you are going to switch to one of their steam engines instead. As for Starlink, it's great for people who have no other options. However it has increased latency and uses CGNAT. Not to mention it is slower then what you can get with fiber.
As for your problem, do you have all the normal lights on the fiber modem/ONT? Have you checked Cox's outage map? If the ONT is online, are you using a Panoramic gateway for your router? If so, what light is on that? If not, what model router do you have?