I once installed a software update in my samsung galaxy S6 T mobile and after that network lock issue occured after that i went to the mobile shop and they unlocked it. But soon after that there is another software update that came in my Samsung galaxy S6? So should i install it  again or not? Because i am afraid that it will network lock again.

So suggest me regarding this issue?

Here's where you can download the stock rom: click here

Hope that helps!

Hey Safiu. you have to download the previous version ROM from the manufacturer website and rename the file to next iteration of the current ROM version , for example current version is xxx.yyy.a.b.111.222 you need to rename the file to xxx.yyy.a.b.111.223 or so depending upon your ROM iteration cycle and copy the file to root directory of the device and restart the device which will install the update(but actually previous version) on restart. This process may not work for all devices but it is worth giving a try.

Note: Backup all your data and try with caution.