: The firmware version you are trying to install is older than the security patch currently on your device. You may need to look for a "downgrade" firmware first.
✅ – Works with any 4G SIM. Tested with over 30 global carriers. ✅ No performance loss – LTE speeds remain same as stock (max 300 Mbps down, 50 Mbps up under Cat.6 CA). ✅ Band locking works – Stops the router from hopping to a weak band. Improves stability drastically. ✅ Web interface is snappier – Less bloatware compared to carrier-branded firmware. ✅ Low memory usage – Leaves about 30% more free RAM (~80–100 MB free) vs locked. ✅ Runs for months – No random reboots or Wi-Fi drops (if you use an official unlock build, not a hobbyist beta). huawei b311-221 unlock firmware