WD Sync on Mac (Sierra) does not connect to my EX2100 NAS

WD Sync on my Macbook pro does non connect any more to my NAS EX2100.
It was working before some updates of the Sierra Operating system.
In the “Cloud Access” Tab of the EX2100 NAS (seen using web access to the NAS) the Macbook pro is properly listed as part of the my “Personal cloud ecosystem”. Yet after the installation of the WD Since app, the connection with the NAS cannot be established and no synchronisation take s place


Try to remove the device from WD Sync, then restart your computer. Once restarted, open WD Sync and add the My Cloud again.
Pause and resume the syncing using the icon on the tray.
If this doesn’t work, uninstall and reinstall the program.

Thanks for your suggestion I uninstalled the software and reinstalled it several times but I didn’t success in getting WD Sync connecting to my EX2100. The strange part of the story is that the NAS is seen in the network, I can login properly, but after the installation no connection takes place and the software hangs in the “connecting” phase …
I also disabled the firewall. I fear that a required port could be disabled, but not in the network because other computers (mac or windows) connect properly

Update for those who might face the same problem: I finally succeeded to make WD Sync working. I discovered that the WD Sync launch agent was disabled. I enabled it and everything is working now !