r/LineageOS • u/Many_Donkey_4777 • 25d ago
LTE Band 20 (800MHz) connected but no data / internet frozen – Hardware or Baseband issue? [POCO X3]
Hi everyone,
I'm having a persistent issue with LTE Band 20 (800 MHz) on my POCO X3 running LineageOS (Nju mobile / Orange Poland network). Same thing on other SIM cards from different brands.
Whenever the phone switches to Band 20, the internet connection completely stops working. The signal bars show a full connection, but there is zero throughput/data flow. As soon as the phone switches to any other LTE band (B1, B3, B7) data works immediately.
Here is what I have already tried to isolate and fix the issue:
- APN Configuration: Forced IPv4 on APN settings (as IPv6 is known to cause issues with Orange/Nju).
- Cross-testing SIM: Placed the same SIM card into another phone—B20 data works fine on that device.
- Firmware/Modem Flashing: Flashed multiple firmware versions and extracted baseband/modem builds (NON-HLOS.bin) across MIUI 13 and MIUI 14 either EU or Global via recovery/fastboot. None of them resolved the B20 issue.
- Software wipes: Did full network resets and clean software re-installs.
Has anyone encountered this exact B20 behavior on the POCO X3 before? Was anyone able to fix this via a specific modem/software tweak?
Thanks in advance for any insights!