Everything works...except Netflix (Orbi RBR50 v2)

I'm an IT Professional, and my buddy hit me up the other day having an issue with his new home WiFi setup.  Turns out he got an RBR50 v2, and a Satellite.

Everything working just great -- no problems.  Except one.  Netflix won't work.  Throws error:

tvq-st-106

In his case, this is on any of several Gen 2 Amazon fire sticks that he has in his house.

I tried to troubleshoot it with him the other day, to no avail, and went over there today, and left unsuccessful.

Everything else works fine, and without issue, only Netflix giving him grief.  I tested on my laptop on the WiFi -- no dice.  The site loads, but none of the images do, and sometimes you can get a video to start, but it always craps out pretty quickly.

I hooked up wired to his Orbi -- same thing.  I hooked up straight to his modem, and it worked fine, everything loaded as expected.  What's even weirder though, is I tried DMZ'ing one of his Fire sticks, and it still doesn't work.  The "Armor" or whatever it's called security is disabled.  I tried several different DNS options, but none of them made a difference going through the router.

I also tried:

Toggling WMM on and off

IPV6 set to disabled

Turned off DoS attack protection

Guest network is diabled, checking the access control and all devices are set to allowed. uPnP is on, and again, literally everything else internet related works fine.  (Firesticks stream other video just fine, PS4's work and can play online, Websites load normally, etc.)

FWIW he's using an Arris SB8200 (also new) and his ISP is WOW! in SE Michigan.  He said he factory reset it the other day (I ran out of time today and didn't have a chance to try this myself).

I'm just at a total loss.  I thought it could be some weird IPv6 issue but again, that reports as disabled in the only IPV6 menu I could find.  He's on the latest firmware (AFAIK -- it ends in .16 and looked to be the same as the most current one on the Netgear site, up since April).

Orbi correctly ID's his Amazon Firesticks, and they're designated as media streaming devices.  Parental controls are disabled, all blocking is turned off, etc.

Anybody have any ideas?  I'm at a complete and utter loss for ideas.  I even talked to my boss, because I know he's set up a few of these things, and he said only thing he's ever had an issue with was getting Satellite's recognized.  Again, I was operating 10 ft. from the main Orbi router, and tried on wireless, wired, and straight from modem.  Only worked from the modem, although after I started a Netflix show on the modem, I unplugged my wired connection to it, reverted to WiFi, and it was able to continue playing -- apparently without issue.

Again, I just have no clue what the issue could be.  It smells like DNS, but the DNS settings that worked straight from the modem are what's currently the setting on the router for DHCP (from WOW!), and I also tried adding in ye old 8.8.8.8 and that made no differnce.

Any suggestions greatly appreciated!