I installed the 7.1.1 update yesterday and my cell data use is off the charts. Most of it is being used up by Chrome. Also, the drop down menu has been actively showing “Configuring your cellular network” since installation without stopping. I’ve been on a wifi network most of this time so I don’t know why the cell data usage is so high.
Sorry for the late response. Please refer to this document, (particularily the “troubleshooting” section.
How to Install System Updates (From Lollipop) – Republic Help
Clearing the Android cache often solves problems after an update. Try the troubleshooting steps outlined in the document and let us know if it resolves the issue you are having.