[code_duck]

It wasn't stated that that was the first thing he tried. I've experienced router/modem issues where only certain sites were inaccessible until one or both pieces of equipment were restarted. I'd be interested in knowing exactly what happens to a router's software to make that happen.

[saraid216]

I'd spitball a guess that it has to do with the firewall rules on the modem or router running themselves into a bad state. That would explain why a restart fixes it, since the state would be cleared.

[jorkro]

That can be caused by a variety of issues. From the top of my head, I would investigate broken DNS caches and incorrect MTU settings.