I made this to run on my raspberry pi which is hooked up to my local network, in order to monitor my internet speed.
git clone https://github.com/dermasmid/internet-speed-log && cd internet-speed-log && sudo chmod +x setup.sh
./setup.sh
The file with the logs will be: /var/log/speed_log.log
Tail the output: sudo journalctl -u speed_log -f
See the service status: sudo systemctl status speed_log.service