2. Even though the router has a 2.5gig port, it only has 1x. So if you're modem is using the 2.5gig port, the other hardwired devices are using the 1gig ports (unless your using lan port aggregation). So those hardwired devices will max out at the 1 gig
3. when speedtesting wireless, did you try other channels on the 5/6ghz? Plus you need to be close to it as those speeds will drop off quickly.
4. Is the ATT gateway in passthrough/modem only mode? Or are you in a double nat.
A double nat happens when you cascade more than 1 router. https://kb.netgear.com/30186/What-is-Double-NAT Fixes? There’s 3 options but only use 1. 1. Put the modem/gateway in modem only/pass through mode. This disables its routing functions. 2. Leave the modem/gateway in router mode but put the Netgears IP address into its DMZ. This forwards the data to the netgear. You can either leave the modem/gateway’s wireless enabled or disabled. Just make sure its using a different wifi channel to prevent interference 3. Put the Netgear into access point mode. This disables its routing functions. Wifi/ethernet still works but it does disable some features. https://kb.netgear.com/26765/Which-features-are-disabled-on-my-NETGEAR-router-when-it-is-set-to-AP-M...
Have you tried leaving the BGW in router mode (disable its wifi) and put the netgear in AP mode? I've seen their passthrough mode not work properly and att has zero motivation to fix it.
