The is a popular LTE Cat6 router (often sold by carriers like Vodafone, T-Mobile, and Telstra). However, due to carrier customizations, users frequently need to flash new firmware to unlock features (like band selection or SMS), debrand the device, or fix boot loops.
You can download and install the latest firmware directly through the router's web management interface: to your router's Wi-Fi or LAN port. huawei b311221 firmware download link