A few months ago I described a method to fix the Searching for Gateway Controller bug in Apple's AST Service Tools.
Apparently they changed a few things in the latest version when running on 10.9.4 or later, and the deleted the aformentioned /LIbrary/Preferences/com.apple.servermgr_info.plist file, so the described fix doesn't work anymore.
Luckily they made solving the issue even easier, and removed the dependency on the original IP the server was configured with. Sadly, they introduced a new bug where the Gateway Manager can't find it's backend services anymore when the primary network interface gets a new identifier. E.g. your Mac reboots and the ethernetinterface changes from en0 to en1.
Fixing the issue
- Make sure your hostname resolves to an IP that's defined in your primary ehternet interface
- Go to System Information and write down the BSD Device Name, commenly known as en0 or any other number for that interface.
- Go to /Library/Preferences/com.apple.gateway.plist and open the file in a texteditor, preferably something like BBEdit that doesn't change the file's stucture while editing.
- Search for the line NetworkInterface and change the corresponding interface en0 to the one you found.
- Reboot the Mac
<plist version="1.0"> <dict> ... <key>NetworkInterface</key> <string>en0</string> ... </dict> </plist>
This hack worked for me in my setup, I'm not responsible for issues that occur when this hack does or does not work on your server.