If you are looking for a firmware link simply to improve speed or stability, consider these safer alternatives before risking a flash:
: Optimizes data processing for better 4G/LTE performance. zte mf79u firmware link better
The XDA community is a goldmine for modem firmware. Look for threads titled: If you are looking for a firmware link
This is a massive Russian tech forum. It is arguably the only place with a comprehensive archive of ZTE firmware files. zte mf79u firmware link better