Wifi connectivity

See these Apple articles below:

If you see No Service, Searching, or SOS on your iPhone or iPad

If you see No Service, Searching, or SOS on your iPhone or iPad - Apple Support

Connect to Wi-Fi on your iPhone, iPad, or iPod touch

Connect to Wi-Fi on your iPhone, iPad, or iPod touch - Apple Support

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

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

Check the router settings -> Recommended settings for Wi-Fi routers and access points

Recommended settings for Wi-Fi routers and access points - Apple Support

(on iPhone with iOS 16.0.3)  If you need your Wi‑Fi password ->go to -> Settings -> Wi-Fi -> tap i in the circle -> scroll to & tap on Password -> tap Passcode. 

->  Wi-Fi password visible. 

If they are On, turn Off Hotspot & VPN.

I am using ios 16.1 not 16.03

I don't say you use 16.0.3.

Contact your ISP.

Did you turn Off the Wi-Fi in Control Center/Control Panel?

If so, turn On again.