Works fine from computer, drops on router

[DisneyJason]

I recently installed AdGuard Home on my TerraMaster NAS. I used the "Community" App vs Docker Image (primarily because the Comm App worked, and I was unsuccessful getting Docker to work).

I "tested" AdGuard for a few days from my primary laptop with no issues and so added the AG DNS to my router. Within a few minutes the phones in the household would drop internet regularly (every few minutes) - the wifi was connected, but the internet was down. Computers had the issue as well although not as often

I assume I've configured something wrong but I'm not sure what...

My Network -
Spectrum Cable Modem EN2251
|
Linksys Velop Mesh <===> NAS with AdGuard Home
|
Devices

I use the Linksys for all the network "connections" - ie DNS, DHCP, etc - my modem only serves/sees a single Linksys device - this has been configured/working for a year.

Ideas?