I've gone through all the troubleshooting steps to get my Firestick to connect. It refuses to connect.

I have two 4K Firesticks, and one 1080 Firestick in the house. Of note, which may only be coincidental, I recently moved to a different internet provider. When I migrated to the new internet provider, it came with proprietary hardware. A WiFi 6 router and two mesh units. My previous internet provider allowed third-party routers/devices. I was using a Netgear Orbi mesh system that was WiFi 5. The Orbi setup just worked, every time, with zero issues. The new system has been a bit buggy. Despite the few bugs, all my Firesticks worked well. and all showed 'excellent' connectivity. Last week, one of the 4K sticks just refused to connect. I assumed it simply decided to die on me, so I moved the second 4K stick to the same AVR and it worked fine. Then a few days later, the second 4K stick stopped working as well. Same thing - It simply will not connect to the network, despite showing great coverage. The third, 1080 Firestick still works fine.

I ordered a new 4K Max Firestick after reading on Amazon that it supposedly works better with WiFi 6 set-ups. I'm wondering if anyone else has encountered similar issues as described?

I'll also note that I have tried to re-set the 4K Firesticks to "factory defaults", and that did not work. They revert to factory defualts, but still refuse to connect to my network.