after iOS 15 update, ipad won't stay connected to my wi-fi

Start here:

If your iPhone, iPad, or iPod touch won’t connect to a Wi-Fi network - Apple Support

If you have a VPN App or profiles installed, or a security App such as Norton, these may be interfering with DHCP and preventing your device from obtaining a valid IP Address for your network. The resolution is relatively simple; may only need to temporarily disable or remove the Security App and/or VPN.

DHCP is frequently used to automatically obtain an IP Address from your WiFi Router. Until your iPad has a valid IP Address to connect to your network, you will not have an internet connection. Disabling or removing VPN and/or the offending security App should allow DHCP to operate normally - allowing connection to your network and the internet.

If this resolves your issue, the VPN and/or security App can be reinstated after the connectivity problem has been resolved.

Got VPN?

Try disabling it or, temporarily deleting it from your iPad.

Re-establish your WiFi connection.

If you choose, re-download the VPN and re-enable it and see if your WiFi connection stays consistently stable, or not.

Good Luck!

I reset the entire iPad to factory, bluetooth off, airplane mode toggle on/off, network settings reset, no VPN settings, all default apps. Didn't even sign into Apple ID, and STILL wifi is intermitment, says either no internet or returns a invalid self assigned IP. Even when it does pull a correct IP, it says no internet connection. Router is not the issue since numerous other devices Apple and other OS connect fine. It's just this iPad 6th Gen 2018 that has been rendered useless.

I’m having the same issue of WiFi not staying connected after the IOS 15 update on my iPhone. I do not have any VPN and have never used one. It may connect for a short time then disconnects by itself. If I leave my house and come back it will not connect automatically, so I have to go to WiFi and physically type the password in.

Hello ~Take a look here:

Restart your iPad - Apple Support

If your iPhone, iPad, or iPod touch won't connect to a Wi-Fi ...

~Katana-San~

After updating my iPad Pro 11 inch to IOS14.8 my iPad will not stay connected to the WiFi. How can I fix?

Did you read the comments/recommendations, in this post, before adding your post?

Yes

So, did any of what had been previosly posted apply to you and, if so, did any of advice/solutions presented fix your WiFi issues?

The problem is not related to vpn or security apps, it is due to updating the software

Do you use a VPN or unneeded security software on your iPad?

These CAN cause issues with Wifi on any iPadOS 15 upgrade/updates.

This is the reason this post exists.

I don’t use a vpn or security app and still have the issues