Hi Peter, I recently do not have this setup handy so I could not peek into to see the issues you reported. My best guess would be something to do with the metrics itself not being used correctly on the dashboard. One way to fix this would be to go into prometheus ui for debugging and check what network metrics are present and compare it with what grafana has for those graph. https://prometheus.io/docs/prometheus/latest/querying/examples/ might be a good starting point if you are not sure how to query metrics from prometheus.
If you do happen to fix it , please create a PR on the github.
Thanks,
Mahesh