Lets get this straight; so your device is able to detect signal (2G and 3G) but not 4G. For 4G VOLTE-only networks like Ntel, that would mean no signal. Your case is different from no signal at all, a situation often associated with Null IMEI.
Whenever you run into no 4G network problems, here are 6 things to try before going on a 1 star rating + negative review rampage 🙂 .
1. Does the device supports 4G?
We’ll start with the noobs. There’s no way you’ll get 4G reception on a device that doesn’t have 4G support. You also shouldn’t expect an OTA software update that’ll give you 4G capability because its a hardware component.
To check if an Android device has 4G capability, you may lookup the specs on websites like VenFinder or check your phone’s Network Settings > Preferred Network Type. You should see 4G or LTE if supported.
If your phone doesn’t support 4G then you’ll need to purchase a 4G enabled smartphone.
2. Is your SIM card 4G enabled?
I was going to leave this point out till I came across a post by someone who swore never again to buy Tecno smartphones because GLO 4G wasn’t working on the model he’d bought. Turned out this fellow was expecting 4G to miraculously popup on a 3G SIM card.
3. Do both the phone and SIM card’s service provider support the same 4G band(s)?
In order for a 4G-enabled SIM to work on your 4G device (i.e receive 4G signal), the device needs to support the same 4G bands as the SIM’s network.
Lets say you wish to purchase a 4G-enabled device which would support Ntel 4G network (smartphone or modem). You first need to find out Ntel’s 4G bands (3 [1800 MHz] and 8 [900 MHz]). Next, you filter your search based on devices which support either or both 4G bands. Here’s a compilation of Nigerian Telcos and their supported 4G bands.
4. Wrong Preferred network type setting
How you get to this setting varies with smartphone but its generally under Settings > Network > Mobile network > Advanced > Preferred network type. Ensure this is set to a 4G / LTE option. For some networks like Ntel, not setting the right APN could cause “no signal” issues.
5. Location or poor reception
You might not get 4G signal due to a poor reception or 4G network being unavailable in your present location. If you’ve checked the above boxes (number 1-4 above) then try testing 4G reception whenever you change location.
6. Incompatible NVRAM / Modem / Region
If your device no longer detects 4G after you’d flashed a firmware then the problem might be NVRAM or modem related. This means you might have just flashed a firmware which isn’t for your region.
You’ll need to backup the NVRAM / Modem file from a working phone of the same model in your region (or global version) then restore to your device. TWRP recovery makes this easy.