Milesight Router supports Internet access by cellular, in some scenario, it will cost more data than it should be, you can follow this article for simple troubleshoot.
1. Check if cellular Ping Detection setting reasonable. You can also expand the interval or disable the ping detection.
2. Check if you are under DDos attack, you can enable DoS/DDoS Protection.
3. Check if you use any VPN or add email alarms in System -> Events -> Event Settings. Both will consume more cellular traffics.
You can use Packet Analyzer to monitor cellular data usage for further troubleshoot.
1. Navigate to Maintenance->Tools->Packet Analyzer, select Cellular0.
2. If you are not sure where the traffic from, you can keep IP Addressand Port blank, it means any. You can also enable Advanced to enter more parameters.
3. Click start until the abnormal data traffic happens then click stop, download the tcpdump log.
4. Import the log into wireshark or other similar software.
5. If you are familiar with wireshark, you can use statistics function of wireshark to analyze which conversation cost most cellular data usage. If not, you can send the tcpdump log to Milesight tech support for further troubleshoot.