BooBox
Occasional Visitor
Does the problem go away when you reboot the modem? If not, next time it happens, connect a computer directly to the modem and reboot it and see if the problem goes away. If it does, is the router. If it doesn't, it's something before the router, probably spectrum. Cable ISPs gaslight customers all the time. I know because I used to work for one. I swear I never did any of the gas lighting but I heard others all the time. Not even fully intentional either. It's just that ingress is hard to track down so it's swept under the rug a lot.