I am trying with Grafana, DataSource Elastic with MetricBeat ingestion, do a panel that gives me the current KBPS of my network adapter.
I tried Derivative and some negative values show up, and the graph its always changing and recalculating.
I want to show the current network bps per second inbound.
I did the average of the system.network.in.bytes and than the derivative of that, but stays with the problem that I refer above.

I may be grossly misunderstanding what you want, but I think you’re overcomplicating things. What is the meaning of bps per second? Bytes per second should be a sum of bytes in a 1 second interval. Average a few of those and you can get an average value of BPS, and then you can do a moving average to smoothen it out. I don’'t know what BPS per second would mean, as maybe you can average bps over a larger interval than one second, but once you have bps that’s one number every second. The derivative of a metric is just the change in value, the slope of the tangent line at any point in the graph, so whenever your average bps is lower than it was before you’ll have a negative value for the derivative. But again, I’m not sure why you need the derivative. You can graph your bps over time, and can display the current value in the legend, if that’s what you’re trying to do.