I recently go Sonic 1Gb fiber installed at my house and I wanted to be able to use the modem in combination with my own router. The ONT that I got is the BGW320-505 and I have a Asus RT-AX3000.
I found that I could configure the BGW320-505 in passthrough mode (although, I seemingly can't turn off the DHCP server) and then use my own router. However, when I do that, the speed that I am getting through the Asus router when using a wired device is very low (~300mbps). When the same wired device is connected to the BGW320, I get almost full bandwidth. Both the Asus and the BGW report that the connection between the two devices is 1000Mbps.
The first question that I have is: how do I properly configure the BGW320 for passthrough so I can use my own router? Secondly, has anyone had any similar experiences with low bandwidth through a secondary router?