Using a tp-link 4G lte, MR6400, v4, as a 4G router. Sudden surge in data use within last 10 days without any obvious cause. Traffic Monitoring [advanced > System Tools > Traffic Monitor] shows a single device, (number 2) using twice as much data as a similararly used device (3). 

q1. Is the Traffic Monitor data accurate? The data usage report from the router is much higher than the data use values from the device.

My main concern is security, is something using a lot of data that I don't know about?

Thanks!