Getting ATT Modem/Router on same network with my Netgear Router

[RoachForLife]

Hey all. I apologize in advance if this is n00b level stuff but basically I have a Pace modem for my fiber internet with ATT and a Netgear R7000 router. Now for the past 6 months I set it up so that all of the routing was handled by my Router and none with the modem. That was fine and good until last month I upgraded my PC to basically top of the line specs (my PC was about 8 years old before this, yikes..). Anyhow, I left it on my router but then one day decided to plug my cat6 from my PC into the modem directly and my speedtest downloads went from 500k to 900k. So obviously my Netgear router cant keep up with the speed.

Ok with that said, my plan was to put all Ethernet devices on the Modem using switches and then handle all the wifi with my Netgear. It seems that the wifi performance on the ATT modem is pretty weak.

Anyhow the issue I have is that my two devices talk to one another obviously but the devices on them do not. For example, on my home PC (ethernet) i cannot ping or connect to say, one of my Wifi cameras, which is on the Netgear. The way I have them set up is that the modem is on the 192.168.1.x network and router on 192.168.2.x line. I tried moving the router to the 192.168.1.x as well but then I cant seem to connect to it at all and doesnt pull internet from modem.

Long strory short any help is appreciated. Also to add I have dd-wrt on the Netgear unit.

Oh and another more basic question, does my plan of putting all the wired devices on the modem/router which seems to operate at almost 2x the speed, and the wifi ones on my Netgear seem to make the most sense, or should I try to load everything on the modem?

Thanks in advance