I am not running El Capitan so this may not help you if your are running El Capitan. I stopped updating at Yosemite 10.10.5.
Get into your MCM dashboard and make sure under Settings-Network AFP is turned on
(for a year I didn’t need this but since the firmware upgrade my Mac won’t reliably connect)
Turn off the WiFi on your Mac then reboot it. I always do a ‘cold’ reboot (complete shutdown then restart) when troubleshooting.
Connect to Server…
In this dialogue box you need to do a few things
Select each individual server that you think is MCM and click Remove
Clear out anything in the Server Address box
Click the little dropdown arrow and Clear Recent Servers
What you’re trying to do here is clear out any references to the MCM that don’t work. Then turn on your Wifi and reboot you Mac.
If this doesn’t work the last thing you can try is in the Connect to Server box type in the Server Address
SMB://192.168.1.2 or whatever the ip of MCM is
SMB://MyCloudMirror or whatever the name of MCM is