I have a very odd problem with my Virgin Media superhub (which is a rebranded Netgear cable modem/router).
After around 1-2 days uptime the computers connected to it will stop being able to communicate with each other in any way. They can access the internet fine, they can sometimes even still ping the router. But they cannot ping each other.
I've disabled all relevant and irrelevant firewalls, the firmware is up-to-date, yet the problem persists until I restart the router.
As soon as I restart the router, they can access shared drives, ping, etc.
I've tried connecting the computers via CAT5 but it doesn't make a difference, so it's not exclusively a wireless problem.