Gigabit Speeds using BGW210-700 in Passthrough Mode

Hi All,

I got Internet 1000 last week.  I originally received a Pace 5268 gateway but have since replaced it with an Arris BGW210-700 due to the confirmed firmware slowdown issue with passthrough mode on the Pace.  I have an EA9200 Linksys smart WiFi router that I've been using since 2015, and when I put the Arris Gateway into Passthrough mode with the Linksys sitting behind it, I'm only getting appx 300-400 Mbps up/down directly connected to my Linksys (I'm doing the bandwidth tests wired, not wireless, for context).

I'm assuming it's due to my Linksys being an older model router. If I wire directly to the Arris gateway, I'm getting the advertised speeds of 950+ Mbps up/down.  I would like to continue using my own equipment, if possible, since I guess AT&T doesn't allow bridged mode to be configured on their gateways.  I don't mind plugging directly into the Arris - for now...but I would like the flexibility of using my own routing equipment in the near future.  I also considered upgrading the router to DD-WRT to see if maybe something on the Linksys is causing the slowdown, but I figured I'd check here to see if that would even help first.

I've read a lot of people are just using their personal router (non ATT router) in AP mode, to extend WiFi range throughout their house, but part of the reason I got Internet 1000 is so I can setup a VPN and host a file server from my home.  I've not actually tried using the Arris as my primary router yet to see if the above is possible (which I'm sure it is), but still, I would like the flexibility of using my own equipment.

Can anyone recommend a router to pair up with the BGW210 to get 950+ Mbps speeds?  Or can someone confirm that the Linksys EA9200 router should be able to see those speeds?

Thanks for any help y'all can provide.