Ipad stops retrying to connect to WiFi

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

I repeat my initial assertion that you problem may very likely be a problem with DHCP on your WiFi network. As a diagnostic exercise, try setting static IP Addresses for each of your iPads instead of using DHCP (automatic) IP Address assignment.

Try a forced-restart - as this will often clear an isolated issue:

• On an iPad with a Home button: Press and hold the top button and the Home button at the same time. When the Apple logo appears, release both buttons.
• On other iPad models: Press and quickly release the volume up button, press and quickly release the volume down button, then press and hold the top button. When the Apple logo appears, release the button.

Are all iPads running the same version of iPadOS? iPadOS 15.5 is current.

If multiple iPads are experiencing the same issue, as described, your difficulties may be due to the DHCP handshake failing on the WiFi network segment. You may need to have your Network Team investigate the underlying issue.

iPad network connection difficulties are usually an indication that your device does not have a routable IP Address - your IP Address usually being assigned by DHCP. When this occurs, your iPad may only have a self-assigned link-local IP address that begins 169.254.x.x.

If you have a VPN App or profiles, or a security App such as Norton installed, these may be interfering with DHCP and preventing your device(s) from obtaining a valid IP Address for the WiFi network to which they are attempting to connect. The resolution is usually simple; if installed, you may only need to temporarily disable or remove the Security App and/or VPN.

DHCP is frequently used to automatically obtain an IP Address. 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.

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