Data usage warning shows up, what should I do?
Data usage warning shows up during use when your mobile data usage reaches the warning level you have set.
How to fix
Please be assured that it is a sign of normal operation. You can simply change the data usage limit setting.
How to setup a data usage limit
1) Go to Settings > Networks > Mobile Data
2) Check the Limit Date Usage checkbox. You will see red horizontal slider bar.
3) Touch and drag the warning line (orange horizontal slider) on the graph to set the warning.