There are various configurable causes in the end device that can lead to increased data consumption. Some of them are mentioned in this article.
a) Retransmission due to poor connection quality
Applications, e.g. via FTP protocol, can abort the transmission of data if the data connection is poor and then attempt to retransmit the packets in their entirety. This can significantly increase data consumption. Ensure that the signal strength of the transmission is sufficient. We have summarised tips for this here.
b) Frequent pings and NTP queries
There are various reasons why pings are sent from the device. For example, keep-alive pings could be used to signal to a server that an end device is still accessible. We recommend setting up such a ping at intervals of approx. 5 minutes to ensure that closed Internet sessions are correctly recognised by the device. If this ping is sent more frequently, then it must be expected that the data consumption can increase significantly. For example, if this were set to every minute, about 1.5MB of additional data would be consumed per day at 56Byte per ping direction. The same applies to time server queries via NTP. Here we advise against a more frequent query frequency than daily, if the terminal is in continuous operation.
We generally recommend setting the MTU size (maximum transmission unit) to 1400, because the best international experience has been made with this value. The MTU size determines how large individual data packets are during transmission. Each data packet contains meta information such as the sender and recipient IP or the packet number. The smaller the data packet is configured by means of MTU size, the more frequently this meta data is transmitted. Increasing the MTU size can therefore lead to lower data consumption.
d) Retransmissions due to transmission errors
In the TCP protocol for data processing, a checksum is transmitted with each data packet and checked at the destination. If this checksum is no longer correct due to transmission errors, this packet is retransmitted. Try to analyse where transmission errors occur in order to avoid them.