I have pretty much the same question as I have a Netgear DG834GT (on DGTeam firmware - V1.03.23 - DGTeam Rev. 1012) but have just purchased an Asus RT-AC68U, shouldnt make any difference compared to the 66U.
I think i am having intermittent DHCP server issues with the GT, sometimes my wifi is connected seemingly but cant access the internet or the routers settings (via 192.168.1.1) (its all working fine then it just lets go).
This could be because i have more wifi and hard wired devices than ever before, best part of 10 wifi and 10 hard wired devices.
I echo the above question, if i set the GT in modem only mode does it disable all other settings? Or do i need to change its IP to something other than 192.168.1.1 (as the Asus uses that and thats what the NAS uses on my network (192.168.1.x range) so would like to keep that format for the DHCP). Say change the GT to 192.168.0.1?
Or again like the above question could I use my DG834GT as is (IP set as 192.168.1.1) but switch off its DHCP server, NAT and wireless connection then connect the RT-AC68U via ethernet, give it an ip address of 192.168.1.2 and enable it's DHCP server (use range 192.168.1.3 upwards say), NAT and wireless connection. Would this work ok?
Oh and PS, i should be able to order Fibre in the next few months, the cab has been installed since August and Samknows is reporting 31/12/14....