Customer has a LAN with a few PCs and some tabs/phones that connect to Internet via their LAN (partly wireless). Internet access is through a 4G mobile modem (other options not available). This has worked well for nearly a year.
Lately they have experienced a lot more data traffic. Since they pay per GB to the mobile operator they try to find what is causing the increased data usage. I have checked the wireless LAN, but can't see anything wrong. Also changed the encryption key.
Question is - is there a way to easily monitor the traffic from the LAN to the 4G network. A packet sniffer might do the job, but results are quite difficult to analyze. Is there an easier way? Thinking of monitoring each LAN IP and traffic to/from the 4G router.