my modem will not stay connected to my router
 

I have a Arris Cable modem, model TM502G, and a Belkin Wireless G router. They have been communicating well for over a year. Lately I would loose my streaming, audio and video. I could not keep a locked link. Then a couple of days ago my connection to the internet went down. I could connect my desktop directly to the modem and have a good connection, even a solid stream. I tried the router again with the same problem. If reset both modem and router i was able to have my internet for a few hours. After that I could reset them and the connection would only last a few minutes. I thought it was my port on the router going bad so i got another router of the same model. I had the same problem. At this point I am thinking it is the modem that is the problem.
Is there some way to test the modem from my side? The Cable company checked it from their end and found no problems and of course they do no support router connections.
Thank you

Does it ping reply?
 

When your router drops the connection, can you immediately refresh the address?.
There is a possibility that your router is dropping ping requests, which causes the modem to not send its DHCP address renewal.
In effect, your router address may be timing out.

Routers in full stealth mode can cause problems with your ISP's ability to determine if you are online and making the request, or if it is just background noise and is being dropped as garbage traffic.

It's something I have seen before, but varies from one service provider to the next.