BGW320-500 -- WIFI drops (shuts off) when plugging device(s) into Ethernet ports

Hi - 

Just moved my AT&T service from my old home to my new home. Lucky we had fiber available here since we had it at the old house.

Anyway, I had the old black router at the old house, where I used IP Passthrough to a Synology RT2600AC. For many years, this was  a great configuration with absolutely no issues.

The installer came out, did a great job, BTW, and had the internet up and running after fixing some old issues from the previous installation.

So fast forward a couple days and I attempted to do the IP Passthrough with the new router (BGW320-500). As soon as I plugged in the Router to one of the available Ethernet ports, the WIFI generated by the BGW320-500 completely shut off. Also, there was no DHCP to the RT2600AC or the laptop I had plugged into another of the available ports - I think they were 4 and 3, respectively (top port and one down from the top port).

So I unplugged both devices and about 30 seconds later, the WIFI on the BGW320-500 came back on and things are back to normal.

I logged into the configuration interface to see if there was any setting I was missing that said something like "WIFI or WIRED ONLY" - but the wired connection won't work at all.

Google rendered very little info without any solutions. Has anybody seen this before?

Yes, I've turned it off and on again.

Best!

Andy