A: Yes, but only from version 11.x to 10.x via the recovery page ( /html/update.html ). You cannot downgrade past the hardware's secure boot floor.
If you want security, stick with 11.0.4.15 stock. If you want performance and features, move to the community-maintained modded firmware based on 11.0.5.15 . Conclusion: Should You Update Your Huawei B818-263 Firmware? The Huawei B818-263 remains a powerhouse in 2025, but only if it is running the correct firmware. If your router is stable and gives you 150Mbps+ without issues, do not update . There is no benefit to "if it ain't broke." Huawei B818-263 Firmware
However, if you are experiencing random reboots, poor carrier aggregation, or cannot lock to a specific 4G tower, a firmware update (or downgrade) is your most powerful tool. A: Yes, but only from version 11