[globular-toast]

That's the part I didn't get. The author said there was no other possibility except the modem, but why? It seems like quite a leap. I would have first suspected a compromised router on the internet. Is it possible that changing the modem caused new routes to be used which appeared to fix the problem?

[Biganon]

Of all the routers along the route, the one most likely to be compromised is obviously the piece of plastic guano your ISP forces you to use