This is what I'd do to fix iPhone does not connect to Wi-Fi with/without a computer.
Method 1 Turn Off & On Airplane Mode
Method 2 Reset Network Settings
Method 3 Force Restart iPhone
Method 4 Refresh iPhone with TunesKit iOS System Recovery
Method 1 Turn Off & On Airplane Mode
Method 2 Reset Network Settings
Method 3 Force Restart iPhone
Method 4 Refresh iPhone with TunesKit iOS System Recovery