I have installed MRTG on Ubuntu 20.04.4 and got it running with:
sudo env LANG=C /usr/bin/mrtg /etc/mrtg/mrtg.cfg --logging /var/log/mrtg/mrtg.log
It is working great. The only problem is when I reboot the server, it stops working. If I log in and run the above command again, it works again until the next reboot.
I must have missed something. Any help appreciated.