Nighthawk R8000 Wired Connection Slower than ATT modem

[ellisonwTX]

I thought my issues were with my AT&T modem, so they swapped it out yesterday. When the computer is wired into the new modem I get 840Mbs. If I plug my computer into my router, and the router into the modem, i'm getting 340mbs.

I am running firmware version V1.0.4.62_10.1.74.

Are there any settings that are causing this to cut the speed down? Yes, I have turned off all the security settings. Yes I've checked the wires.  

[plemans]

What att modem are you using? 

Is the att device in passthrough/modem only mode? Or the netgear in access point mode? 

make sure that access control, traffic monitoring, qos, and parental controls are all disabled. 

I'd even recommend a full factory reset and manual reinstall if they ever were enabled. Reason why is I've read of settings being retained even through the services were disabled.