Try these threads regarding remote access issues, with a WD Staff response today:
Did you check that your external IP address hasn’t changed?
I know you said your (internal) IP address is still fixed, but are you sure it hasn’t changed? If you have set up port forwarding rules, they may be trying to redirect to a previous IP address (although my router associated port rules with MAC address, not IP).
The other usual suggestion for weird behaviour is escalating resets (4 second, 40-second power-up: see the User Manual for details).
