And I did a factory reset again to see if it fix it like the first time. Two came back online for a few minutes, then they all went to not responding. And you call Comcast they don’t know nothing.
I can't tell you how sorry I am. I had major HomeKit issues last night, but it was caused by a single device, a plug. I just reassigned the plug from one node in my mesh network to another (I use Asus routers with mesh support). It brought everything offline. I was screaming in frustration for an hour, trying to get everything working again. It's so fragile.
So your thread network is fine - the devices are communicating over it to each other. But your thread border routers (the Apple hubs) are having a problem talking to your Comcast router. Your phone communicates to your thread network through the border routers using WiFi.
When you reset your router, make sure you had unplugged it and left it unplugged for a few minutes before plugging it back in.
Do any other devices have a problem with WiFi using the Comcast router? Do you live right near someone who has a strong WiFi signal that could be interfering? Comcast routers do saturate things a bit with their hotspot and hidden networks. I bought WiFi Explorer and it has been very illuminating regarding this.
https://apps.apple.com/us/app/wifi-explorer-scanner/id494803304?mt=12.
I know this might hurt, but you could do what I did. You could "bridge" your Comcast router and buy your own WiFi router to handle WiFi connections. The web interface to the Comcast router has a toggle that will do that. It was painless for me to do that. Comcast does support this as a valid approach. For me, the Comcast router retained the IP address I had set before bridging. So I am easily able to toggle it back to non-bridged.
You could also attach a new router to your Comcast router without bridging it. Make sure you turn off the Comcast router's WiFi if you do that. There are subtle consequences with router-to-router setups, but I lived with that situation for years before bridging the Comcast router and had no problems at all.