I upgraded my small server to Mac El Capitan. I was running FMS 13. Everything seemed fine. Then I upgraded FMS 13 to FMS 15. Now I can only connect from the computer in my office which happens to be plugged into the same router as the server. No clients outside that space can access FMS 15.
I followed uninstall/install directions carefully
I went back and double-checked server settings.
The connection is failing on Web login also