|There's no such thing as "router overload". Home routers normally handle at least 32 clients w/o getting loaded down so that's not the problem. |
Your router might be defective and that it works after being cold-cycled indicates this. However I'd also suspsect transient network problems, ie., Comcast's server is hiccuping and not accepting packets suddenly.
To save wear and tear on your knees I'd suggest that instead of going downstairs to reset it next time fire up your browser, go into the configuration screen (usually 192.168.0.1 or 192.168.1.1), and do a warm reset. Meanwhile check your connections to make sure it's nothing as simple as a loose cable. Ping the gateway IP address to see if you get a response back. Update the router firmware from the manufacturer's website and make sure that your clients are all up to date on their patches. Scandisk and defrag them then run an AVS to make sure you haven't picked up a bug somewhere.