New phone wont stay connected to wifi
My phone keeps dropping wifi
iPhone 12 Pro Max, iOS 15
Optimize the range of the mobile network, see this Apple article:
If you see No Service or Searching on your iPhone or iPad
If you see No Service or Searching on your iPhone or iPad - Apple Support
Read again -> Related Article -> If your iPhone, iPad, or iPod touch won't connect to a Wi-Fi network
Check your router settings -> Recommended settings for Wi-Fi routers and access points
Recommended settings for Wi-Fi routers and access points - Apple Support
If they are On, turn Off Hotspot & VPN.