I've only just tried using channel_up and channel_down as api commands and there seems to be a bug.
The commands do work and the channel changes as expected but I get a ""RequestError: socket hang up" error from the http request node that I call it from in Node Red. Then ECCONRESET appears below the request node.
I'm using exactly the same command format in node red for many other api calls which work fine without the error it just seems to be channel_up and channel_down that cause the issue.