Re: fedora 26 vncserver with black screen
Shot in the dark here - I think you have to be logged in as a valid User on the machine from which you attempting to connect. I suspect the userid gets passed to the remote for validation. Also, on my CentOS system, that user must be logged in also on that same 'target'.
Additionally, Sharing has to be enabled on the target (for that user).
There was one other issue I had that doesn't currently come to mind. Hmm. Hopefully, this is of some help.
Change - the only constant.