Did an update in Fedora 27 for KDE and now KRDC no longer connects to my Windows 10 machine. It will show the connection dialog, prompt for my password, and then immediately disconnect. Nothing shows up in journalctl or when I run krdc in the terminal.
Sorry not a KRDC bug after all. Turns out a recent change in Windows broke freerdp. Updating to the latest freerdp package in updates-testing fixes it.
*** Bug 403299 has been marked as a duplicate of this bug. ***