The WG3526 that is running our Rooter Firmware, can monitor the data usage. While it is not a perfect representation of the data usage via cellular, it does allow a close idea of your consumption. However, do not use the Bandwidth monitor as an exact measurement of your usage.
To
If your device is factory reset, it may wipe out the necessary APN settings (Connection information for the network to know how to connect. This will walk you through the easy steps to check your APN:
In your web browser, go to the address 192.168.1.1
The default password is: admin
On the left side tabs, select Bandwidth Monitor and then click ROOter Bandwidth Monitor