The ZTE Z970 appears to be missing LTE Band 5 (850) that AT&T uses in some areas. Might want to check if this band is used in your area. For LTE AT&T uses bands 2 (1900), 4 (1700), 5 (850) and 17 (700). Band 17 is AT&T's primary LTE band. Latest ZTE Flash Tool ( the best ZTE Smart Phones tools ) is released and available to download without waiting. so, If you already using its (ZTE) old version on your PC / laptop, Then you are required to new update ZTE-setup file.
Hydra Tool – Qualcomm V220.127.116.11. Release Notes: Hydra Tool - Qualcomm Qualcomm Flashing seamlessly easy with Fastboot and EDL mode is supported , Intelligent FRP removing with lots of models supported already with the Hydra Tool There are unlimited operations and complete Qualcomm functions supported in Hydra Qualcomm Tool where as also you can operate with lots of models supported already .