If your iPhone is automatically switching from Wi-Fi to Cellular, you can find below the steps to fix the problem of iPhone switching from Wi-Fi to Cellular Network.
Wi-Fi Keeps Switching to Cellular on iPhone
While iPhone switching from Wi-Fi to Cellular network can be a problem for those on a limited data plan, it can also be problematic for those on unlimited data plans.
For example, you won’t be able to use Chromecast or Print to a wireless printer, if iPhone switches to Cellular Network and gets automatically disconnected from your Home Wi-Fi Network.
1. Check Your Internet Connection
A common reason for iPhone switching from Wi-Fi to Cellular is due to poor Wi-Fi network connectivity.
Go to Settings > Wi-Fi and make sure that iPhone is connected to Wi-Fi and the network strength is good.
If Wi-Fi network strength is weaker than Cellular, the Wi-Fi Assist feature on iPhone automatically switches it to cellular network.
If you are experiencing Wi-Fi connectivity problems, you can refer to this guide: iPhone Keeps Disconnecting from WiFi.
2. Turn OFF Wi-Fi Assist
Switching OFF Wi-Fi Assist feature has helped users to fix the problem of iPhone getting disconnected from Wi-Fi.
Go to Settings > Cellular > disable Wi-Fi Assist by moving the toggle to OFF position.
After disabling Wi-Fi assist, reconnect to your Wi-Fi network and see if Wi-Fi is now working on your iPhone.
3. Restart iPhone
The problem could simply be due to a stuck program or process and this can be fixed by restarting your device.
Go to Settings > General > Shut Down. On the next screen, use the Slider to Power OFF your device.
Allow iPhone to completely Power OFF > Wait for 30 seconds and then Restart iPhone by pressing the Power Button.
4. Switch OFF Cellular Data
You can temporarily switch OFF Cellular data and force iPhone to use WiFi Network.
Go to Settings > Cellular > move the toggle next to Cellular Data to OFF position.
This will completely rule out the possibility iPhone using Cellular Data and restrict your device to Wi-Fi network.
5. Reset Network Settings
The problem could be due to a change or corruption in Network Settings. This can be fixed by resetting your device to default network settings.
Go to Settings > General > Transfer or Reset iPhone > Reset > On the pop-up, select Reset Network Settings option.
On the confirmation pop-up, tap on Reset Network Settings again confirm.
After this, connect iPhone to WiFi Network and see if the problem of iPhone switching from Wi-Fi to Cellular is fixed.