Hello abhishek-kaisar,
Thank you for reaching out to Apple Support Communities.
These steps may help:
"Reset your network settings
If you're using iOS or iPadOS 15 or later, tap Settings > General > Transfer or Reset [Device] > Reset > Reset Network Settings.
If you're using iOS or iPadOS 14 or earlier, tap Settings > General > Reset > Reset Network Settings.
This also resets Wi-Fi networks and passwords, cellular settings, and VPN and APN settings that you've used before."
More details and other steps can be found here: If your iPhone or iPad won't connect to a Wi-Fi network
If the issue persists, can you provide a few more details? Does this happen across multiple networks or just one network? When did you first notice this? Also, what is your exact iOS version?
Cheers!