Call your network service provider If at this point, your phone is still not showing or connecting to a 4G network, you need to contact your network service provider. There may be a network outage in your area, something is wrong with your line, or perhaps your carrier is having a network upgrade.
Update your iPhone or iPad to the latest version of iOS or iPadOS. Go to Settings > Cellular. Then: For iPhone, tap Cellular Data Options, then turn on Enable LTE.
Go to Settings > General > Transfer or Reset [Device] > Reset > Reset Network Settings. This will also reset Wi-Fi networks and passwords, mobile data settings, and VPN and APN settings that you've used before.
Press Settings. Press Mobile Data. Press Mobile Data Options. Press the indicator next to "Enable 4G" to turn use of 4G on or off.
If 4G or LTE is available from your provider, you can switch to a 4G network in your cellular or mobile settings. If you don't see the 4G or LTE option on your Android and are sure your phone is compatible, dial #*#4636#*#* to enable the feature. Some carriers do not allow you to change your network type.
Open Settings and tap Cellular. Make sure the switch next to Cellular Data is on. If it's already on, try toggling it off and back on again quickly. This can sometimes fix a minor connectivity issue.
Restart your device.
Open your Settings app and tap Network & internet or Connections. Depending on your device, these options may be different. Turn Wi-Fi off and mobile data on, and check if there's a difference. If not, turn mobile data off and Wi-Fi on and check again.
As we shared in the blog post, 4G to 5G: How Long Will 4G LTE Be Available, the main reason for network shutdowns is that the carriers have limited spectrum available for expansion.
The growth of 5G networks doesn't mean 4G is going away. Mobile carriers will use existing 4G LTE networks to provide their customers' cell service well into the next decade. 5G networks will work with 4G — not outright replace it. The upshot is that 5G-capable cell phones will still use 4G technology.
Check Your Cellular Data Options
Your iPhone gives you the ability to pick and choose which cellular networks your iPhone can connect to. Head to Settings -> Cellular -> Cellular Data Options -> Voice & Data. Make sure that LTE is selected. If you have a 5G iPhone, you can also select 5G here.
Ensure your SIM card and phone are 4G-compatible
Though most modern phones are built with 4G (and 5G) chips, some entry-level devices feature only 3G networks to save cost. Even so, if you have an old SIM card that has not been upgraded to 4G, your phone won't so 4G.
From the home screen, choose Settings. Tap Mobile or Cellular. Check Mobile Data is on, or switch it to on (the switch will show green). Check 4G is on, or switch it to on (the switch will show green).
Go to Settings, Network & internet, then tap on Mobile Network. Select Network mode. A pop-up list of preferred modes will appear. Tap on Auto or the fastest (2G/3G/4G/5G) option.
4G is the fourth generation of mobile phone technology and follows on from 2G and 3G. 4G provides up to 3x faster data speeds depending on the amount of people using it (congestion) and location (coverage). To enjoy 4G you'll need: a 4G SIM.
Reset your network settings
If you're using iOS or iPadOS 15 or later, tap Settings > General > Transfer or Reset [Device] > Reset > Reset Network Settings. If you're using iOS or iPadOS 14 or earlier, tap Settings > General > Reset > Reset Network Settings.
To fix iPhone service, turn Mobile Data and Airplane Mode on or off, and update carrier settings. You can also try restarting and updating your iPhone or removing and re-inserting the SIM card. If all else fails, contact your network carrier or Apple Support for assistance.