Unsure about where to locate the hardware version for my Decos

Deco x20 3-Pack connected to Verizon FiOS 300/300. 3-story townhome with low interference, 1 Deco per floor. 

Guest Network: OFF; Operation Mode: WiFi Router; Firmware indicates up-to-date via Deco App. 

There are roughly 74 devices if everything is on and connected.

We have a number of wifi IoT devices on  2.4ghz and several devices wired in to a TP-Link 8-port switch connected directly to the Main Deco. 

I have seen multiple threads about VERY similar issues, but none of them seem to have a solution, so taking a shot at reopening the question... I am past my return window and REALLY frustrated. 

Purchased in June 2022 to replace aging Google Wifi mesh system. 

No issues for several months. 

Beginning in October, we began experiencing intermittent INTERNET drop-out for individual devices- Specifically, these devices would indicate a connection to the network, but no connection to the internet, this includes both wired devices and wifi devices. This became problematic to the point where I reserved IPs and prioritized my wife's devices as she was having to turn on her cell hotspot to get work done. Then in late December, the internet connection to the network entirely died. After much troubleshooting and working with a Verizon Tech, we determined that it was the Decos- devices connected directly to the FiOS ONT worked fine, but Main Deco was getting a connection for a few minutes then dropping out. 

I swapped cables with no luck. 

I switched modes from Router to access point with no change.

I thought that particular Deco was bad, but had precisely the same issue after reassigning the Decos. 

I attempted removing some devices to see if there was a corrupted or hacked device on the network with no change. 

I finally deleted my network and started from scratch. 

After completely recreating the network, the internet connection restored but the device issue stayed the same. So I ventured onto the threads here for insight... no useful advice, but one person dropped their network to just 1 Deco, so I gave that a try. This has worked for about 2 weeks, mostly, except now I am again having issues with devices dropping off of wifi, or being connected to wifi/network but not able to access the internet. 

I have observed my devices constantly popping on and off wifi, and several devices behave like they've been blocked from the network, though I have no blocked devices. 

I am hoping someone has figured this out, or that TP-Link has something that can help as this is becoming infuriating. I am nowhere near the device limit, I have a very clean setup overall, our usage is well below the capacity on the network... What am I missing???

Thanks