Keep rebooting

Hello everyone,

I have recently purchased the Netgear C7800 modem router, troubleshooting has been completed by a Xfinity technician nothing went wrong with Comcast network, were able to capture all 24 downstream channels as well as 4 upstream channels. (The best they can offer even they sell that as Gigabit network)

However, the issue with this modem router is that it will keep rebooting itself non-stop if I am let it start with 10 devices, three plugged directly into the modem router, and seven plugged in via a switch. All configuration are the same with the R8500 that I had before, and never freeze like that. The only way to resolve this issue now, is plugging in the device one by one, like once started, then plug in the device, one minute at a time, then it will not freeze like in that way. 

Anyone else could give me a better suggestion to it? I might be able to do some more troubleshooting later on, like disabling DHCP and let all devices have a Static IP, it might help not to freeze the device after reboot. I don't know yet, but I just don't want my ATA devices be connected via wireless for now.

Let me know how you guys think. Thanks :)