Here is a list of things to consider when troubleshooting network connection issues on your phone:

1. Check your device settings
   Take a look at your network connections on the device and ensure they are set to the correct network. Check network and internet sharing settings, Wi-Fi settings, APN settings and Mobile Network settings.
2. Restart your device
   A simple restart can help clear minor network issues. Once your device is back on, take a look at your connection again.
3. Verify you have adequate coverage
   Confirm your device is in an area with adequate coverage to make and receive calls as well as send and receive data. You can also check with your service provider about coverage in your area.
4. Check your SIM card
   An improperly installed SIM card can cause issues connecting to your network. If you have had your SIM card swapped, make sure it is inserted correctly and firmly in your device.
5. Try connecting to another network
   If possible, try connecting to another network. This will help you further diagnose and confirm if the connection issue is related to your device or the network itself.