Wi-Fi not working after iOS 15.2 update

See this Apple article: If your iPhone, iPad, or iPod touch won’t connect to a Wi-Fi network

https://support.apple.com/en-us/HT204051

Yesterday, both of our 6th generation iPads (wifi only) and our iPhones 8 and 11 were using ios 15.1. All were connected to our wifi and working fine. One by one we updated to ios 15.2, and one by one we lost connectivity to our wifi and cannot reconnect no matter what we try. I have rebooted, reset network connections, reset the modem, looked at vpn connection (which is moot because we didn't use vpn with anything), and removed apps. I am worried now because you need wifi to be able to do everything on the iPads and to be able to update on all. How can I do that without access? I need help.

I have just reset router to factory settings - no change.

I am now searching for VPN-based ad blockers - I don't know of any I would have installed, so I guess I will through each app and see??

wifi works on my computer, so it is working...I guess I could go to a store and use their wifi to see if that helps

Update - After wiping clean one iPad thinking there would be a hidden VPN or ad blocking app on it that was stopping the acceptance of wifi, the wipe showed it changed nothing. Frustration was high, so called our internet service provider to see if the modem was the problem. The firmware on the modem was updated remotely and one iPad and the iPhone 11 worked off the wifi for a very short period of time - then nothing. This actually caused our smart tv to stop working as well.

After doing three factory resets of the modem, it was then not even on the list of available wifi networks. We had resigned to the fact we needed a new modem and planned to go and get one the following day. Then, as if with some sort of divine intervention, the wifi came back to all devices.

So to sum up - the ios 15.2 update caused all of our apple products to not recognize our modem; after checking all apps to look for a VPN or ad blocking conflict, we found none; the service provider updated the firmware on the modem; after several factory resets of the modem, it finally worked.

Did uou reset the touter to factory settings, not just a reboot?

It is almost always router or VPN. How about VPN based ad blockers?

Try wifi at another location.

check Settings, General, VPN & device management for a profile.

Did that earlier...no VPN connected. Nothing is listed below that either

Thanks for the detailed feedback.

Like I said "It is almost always router or VPN"