Do you still have the N66U? If so, that would probably be my first choice, followed by your DIR-835. With the CGN3 connected to a follow-on router, regardless of whether the CGN3 is set to Gateway or Bridge mode and the follow-on router is set correctly you should end up with a stable configuration. I think it’s just a matter of having the router set to correctly match the operating mode of the CGN3. I restart my CGN3 on a daily basis, more out of habit than anything else and I never have any issues with it, but the latency issue is still something to think about. I don’t game, so I don’t notice it like other users would.
Regardless of what router you use, check to determine if there is a firmware update available. There have been security issues come up lately that have required manufacturers to issue updates.
If you try the DIR-835, check the connected Port LED at the back of the CGN3 and ensure that it is amber (yellow/orange) in colour which indicates an interconnect rate of 1 Gb/s. If it’s green, that means that the interconnect rate is 10/100 Mb/s which results in throttling by the CGN3. The router has gigabit LAN ports but there is no specification that I have found that indicates that the WAN port is also rated for 1 Gb/s, and there have been routers manufactured recently with very fast wireless networks and slow 10/100 Mb/s WAN ports. So, just to be prudent, don’t assume that the two devices are running at 1 Gb/s for the interconnect rate. The same holds true for any router actually as the amber LED will confirm that the port on the connected device is running at 1 Gb/s and that the connecting cable is damage and error free. There are “fast ethernet” cables around that only support 100 Mb/s, which, if used, end up slowing down the interconnect rate, and causing confusion at the same time. The port LED will confirm the actual situation that you happen to have.