Q: No mobile service after iOS 9.1 upgrade to iPhone 6s

This is just me sharing an issue I had and how I managed to fix it.

After I updated to IOS 9.1 on my iPhone 6s i could not get a carrier signal. I googled and it said to go to settings>general>about and wait for a carrier update. I waited and waited but it never happened.

I kept doing a hard reset on my phone but still nothing. I downloaded the IPSW file for IOS 9.0.2 and was ready to downgrade.

Before I did I just checked through the menus one last time to make sure I wasn't missing anything and went to settings>carrier and decided to take it off automatic. After a few minutes searching for carriers my particular carrier came up and I selected it. Instant signal. I did a hard reset and then went back to carrier and put it back on automatic and lost the signal. Did another hard reset (without taking it off automatic) and it came back on with full signal.

Have no idea why but it worked for me

Thanks