Once you have the correct .bin or .imgz file via the official hot link, do this:
If you are trying to jump from a very old version to the newest one, you may need an "intermediate" firmware. Search for a "Middle Version" firmware for your specific model. mobily connect 4g router firmware update download hot link
Once you have the verified file:
For obsolete models no longer supported by Mobily, sites like drivers.softpedia.com or device-drivers.sa may host archives. If you use these: Once you have the correct