why i cant update my phone it said connect to wifi but it already connected

The only Apple server currently having an issue is Apple's iCloud mail server and it is only affecting certain users. You can always check this by going here -> https://www.apple.com/support/systemstatus/

You can attempt it by connecting to your computer and updating as the The Little's helpfully provided but if you want to do it over the air make sure that you have a good WiFi connection, you are not using a VPN, you have a 50% battery charge or better (and preferably connected to power), not in low power mode and you have at least 8GB of free storage.

Incidentally, if the Apple Upgrade server really was having a problem you wouldn't be able to update via computer either.

yulahm Said:

"why i cant update my phone it said connect to wifi but it already connected"

-------

Why the Issue?:

There is an issue connecting to Apple's servers.

So, Use a Computer: Update your iPhone Using a Computer - User Tip