Since it appears to be purely software -respectively firmware- related, the following posting proved helpful in other cases, albeit none related to this firmware so far.
Quote:
If you encounter not working remote problems that are gone if you disconnect the WDTV from the network, this is a strong hint for DNLA interference problems. Locate other network devices in your network (especially routers) and try to disable or modify the DLNA settings until you find the interference source.
Should you decide to re-install this FW once more to satisfy your own (and my…) curiosity 
disconnect from network and reboot or powercycle.
