Graph like shark teeth

Hello guys,

I’m using The Dude to monitor a device running the VyOS. But the graph is not right.
Look at the image below:
gra02.jpeg
Every other devices that I’m monitoring the graphs are right.
So, my questions are:
Is there some change that I need to do in The Dude configuration to get a better graph?
Is there some SNMP particular configuration that I need to do?

If someone could help me, It would be be great.
Thanks in advance.