a) Try to restart your phone.
b) Move to an open area with a better signal and try again, or contact your SIM card operator to check the network coverage at your location.
c) Swipe down to access the quick settings menu from any screen. Click the Airplane/Aeroplane icon to enable Airplane mode, then disable it after a few minutes. Then check your network connection again.
d) Put your SIM card into another device to check whether the issue is solved. This test will identify whether the issue is with your SIM or device.
e) If there is a protective case on the phone, see if the issue is solved after removing it.
f) Try to reset or update your device. (Refer to Q How can I perform a factory reset on my phone & Q How can I upgrade my device).
If the previously described options do not help, you can contact our hotline or repair center to get more professional technical assistance. Find the hotline or repair center information from the TCL website or APP “Support Center”.