Netgear WNR2000 router loses internet connection

Hello

I have Time Warner (Road runner) internet and I'm using two mac books to wirelessly connect to a Netgear WNR2000 router (firmware 1.2.3.7). Cable modem is Ambit Modem U10C018. After starting downloads I lose my internet connection (not the router connection) usually within 20 minutes. The download speed is usually 500 KB/s- 1.6 MB/s and UL is 159 KB/s. I have to restart the router to regain my internet connection. Both the router and cable modem appear normal when I lose the internet connection.
Netgear suggested I change wifi channels (which I did) and nothing changed. They also mentioned to restart the router which only temporarily solves the issue. It's very annoying to have to restart the router numerous times a day. Time Warner says its the router and refers me to NetGear.

This happens if I'm hardwired to the router or are connected wirelessly and downloading files. It only doesn't happen when I connect directly to the cable modem.

Any ideas how I can solve this? Change MTU? Limit connections?