Disconnecting MyCloud from my router, even briefly, causes my MyCloud to re-boot.
MyCloud reboot destroys any changes you may have made via the Twonky UI (webpage), unless you have taken steps described in my FAQ:
http://community.wd.com/t5/WD-My-Cloud/FAQ-Twonky-DLNA-Media-Server-Setup-amp-Use/td-p/858810
If you put the old router back, do you restore DLNA access? If yes, it’s a router problem, if no, check the following:
[d’oh! You’ve already done that… Does the router have a UPnP media server? Mine does. Is it enabled? My router also has some UPnP enable switches, but I think they’re for controlling the router firewall, but yours may be stricter, or have more versatile control settings. Have you read the router manual…? Are you sure that the network config hasn’t changed? If both routers are using DHCP for IP allocation, it’s likely they will change, and you may have to point your media client at the new IP address]
In the Dashboard:
Check that the Media Serving control on the share containing your media is turned on
Check that the Settings|Media|Media Streaming is turned on.
In the Twonky UI:
Check that the correct share locations and media types are correct.