Beyond the troubleshooting steps already tried, do you have any security Apps (such as Norton) or VPN installed on your iPhone? If yes, these may interfere with AirPrint/AirPlay/WiFi Hotspot or other Apple services. If present, it may be necessary to temporarily remove such Apps from your iPhone - and then perform a forced-restart.
Force restart iPhone - Apple Support
If you continue to have difficulties, check to see if your iPad is using the new WiFi Private Address feature. This feature is intended to provide additional privacy and security when using “public” (untrusted) WiFi networks.
Settings > WiFi > [Your WiFi Network / SSID] - tap the “i” icon - Private Address
The Private Address feature is largely unnecessary for your home WiFi network; if enabled, Private Addressing can interfere with anticipated operation of other devices, such as AirPrint/Airplay. In such circumstances, you may need to disable this feature - and can be enabled or disabled for each individual network.
Use private Wi-Fi addresses in iOS 14, iPadOS 14, and watchOS 7 - Apple Support