Today I put a lot of attention on the AC power leads into the Spectrum router and modem (they're separate devices), with particular focus on the modem since the RF takes down the internet completely.
I used one mix 31 1.4" DI ring with 8-9 turns on the modem, and a couple of 1/2" snap-on's with 4 turns each on the router, and it worked. I'm cautiously excited that I finally solved this issue, and here's where I ask a stupid question since I'm learning and really don't know.
More turns (on both power cables and network cables near the box) through large ferrite toroids is what helps reduce RFI emissions from my ethernet routers. So it has to help the other way as well, keeping high powered RF from getting inside the box.
If you haven't already, you might also try common mode chokes on your feed lines near their shack entrance, to make sure common mode RF near your walls isn't putting too much RF into your house wiring (potentially causing other electronics in your house to eventually fail).