Most routers show an overview of all connected devices, some show a snapshot of the bandwidth used, but hardly any give an overview of the amount of data consumed over a certain period of time and certainly not by which device it was consumed. To make the consumed bandwidth a bit more transparent, I was looking for a way to historically record the bandwidth per device. The firmware of normal routers hardly offer a possibility here, differently when using an open source firmware, for example OpenWRT, see: Alternative Router Firmware: OpenWrt and no longer DD-WRT.

OpenWRT

OpenWRT is OpenSource and can therefore be customized as desired, so far the theory: Practically, however, I could not find a usable package for the LEDE web interface. The available software packages for OpenWRT do not integrate into its web interface and feel a bit outdated. Nevertheless, the extensions presented here provide a good overview of the consumed bandwidth:

bandwidthd

bandwidthd can easily be activated in OpenWRT's packages and provides an overview for daily, weekly, monthly and yearly traffic, as well as charts for total consumption and for each individual device.

To activate the package in OpenWRT, go to "System", "Software", "Update lists ..." and then search for bandwidthd and install it:

The statistics can then be accessed outside the router's web interface using the router's IP and /bandwidthd, e.g.: http://192.168.0.1/bandwidthd

Yet Another Monior (YAMon)

YAMon is not directly available through the OpenWRT packages: A bash script is provided for installation. To store the statistic data I used a USB stick at the router on which I also put the installation script in advance: yamonxxxinstall.sh, see usage-monitoring.com/. The terrible homepage of the manufacturer was quite deterring for me in the beginning, the software itself also seems extremely old, but is not that bad and still offers a lot of statistics. The installation is then done by connecting via ssh to the router, as a prerequisite I also installed the packages for accessing the USB stick and mounted it:

opkg update && opkg install block-mount e2fsprogs kmod-fs-ext4 kmod-usb3 kmod-usb2 kmod-usb-storage darkstat
block detect > /etc/config/fstab 
uci set fstab.@mount[0].enabled='1' && uci set fstab.@global[0].check_fs='1' && uci commit 
/sbin/block mount

cd /mnt/sda1
./yamon347install.sh

The call is then made via the router IP/yamon, e.g.: http://192.168.0.1/yamon

YAMon offers much more information, but in my opinion it is a bit more confusing than e.g. Bandwidthd.