Sony Xperia XZ1 Manual page 24

If your device is not receiving any network signal, or the signal is too weak,
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contact your network operator and make sure that the network has coverage
where you are.
Make sure you have set your device to use the network type that your SIM card
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supports. Contact your network operator if you don't know which network types
are supported.
To select a network mode
1. Find and tap Settings > Network & Internet > Mobile networks.
2. Tap Preferred network type, then select a network mode.
Make sure that your SIM card is working properly. Insert your SIM card in
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another device. If this works, it is probably your device that is causing the
problem. In this case, contact the nearest Sony Mobile service centre.
Search for a network from the device to check if any networks are available.
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To search for available mobile networks
1. Find and tap Settings > Network & Internet > Mobile networks.
2. Select a SIM card.
3. Tap Network operators.
4. Select a network in the list that appears.

If there is no mobile data connection, try the following:
Turn off your device and then turn it back on. By doing this you turn off all
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running applications and free up memory, which sometimes automatically solves
the issue.
Deactivate STAMINA mode and restart your device. To save battery power,
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STAMINA mode disables mobile data when the screen is turned off.
To disable STAMINA mode
1. Find and tap Settings > Battery > STAMINA mode.
2. Tap the slider to disable STAMINA mode.
To restart your device