Interesting. I've had this issue a few weeks ago but I didn't have redactor installed either. I have no idea what I did to fix it, and the others couldn't reproduce. I'll have to wait until it crops up again, but the fact that a plugin might have interfered is a good hint, thanks!
Here is all you have to put in your serever config for NginX
Edit: Looking at your screenshots closer, I see this link. So the point you are missing is that nothing here is changing NodeBB. NodeBB always runs on 4567 in this case.
I think i have this same problem, how do i make it listen on 80?