This thread has made by brain hurt. My observation is that there has been a lot of discussion about exotic equipment, but none about the architecture in the home.
Now I know there are more knowledgeable experts here on the nuances of equipment. However, over the years I have been involved in many diverse installations.
What I do know for certain is that any engineering project is founded on a sound reliable architecture plan, that is the simplest and most logical that can be devised. Now know this sounds harsh, but from the first post, it seems to me that there is no coherent architectural design in his set up, and that it is of the "dog's dinner" variety. What I do know is that good elegant architecture is the very foundation of system reliability.
So when I planned this house five years ago now, I planned the Ethernet architecture to the very last detail and supervised its construction and installation.
There are a vast number of units connected to the internet in this home. All fixed units hard wired, and mobile units Wi-Fi. There is a cable modem, and the Netgear Orbi mesh system, that gives even Wi-Fi throughout the home. So it uses a logical flow, of local hubs, two 19" rack hubs in the studio chase and a 19" patch bay. In four years there have been zero failures. I have done video conferencing without issue.
Any failures have all been on Comcast's end, and in fairness they have been few and brief. My biggest issue with them is that the download speed is fast, but the upload slow. The service is copper, but it connects to fiber at the main roadside box. All the circle boxes are passive.
So my point is that the OP has a complex system, and I think sorting it, starts by committing a sound plan on paper, that is reduced to its simplest and most logical elements.