When starting the WD 2go app, in iOS at least, the app does an immediate mDNS (multicast DNS) query to the paired hostname of the WD 2go server.
For example, I have my app peered with an MBLD named BIGNAS3
I see an immediate mDNS query for the hostname BIGNAS3.local.
The query is sent using IP Multicast Group 188.8.131.52, using the ethernet multicast address 01.00.5e.00.00.fb.
If something in the user's network is not properly forwarding the multicast packets, then it's going to fail to find the device "locally."
It may be that some people's routers / Wireless APs do not handle multicasts correctly. That'd be a pretty serious problem.
Anyway, if mDNS lookup fails, the app will then try to find the registered name of the device using regular DNS. The registered name is assigned by WD when the WD 2go "Server" (MBL, MBL Duo, N900C, whatever) is set up for web access.
In my case, it's BIGNAS3.deviceXXXXXX.wd2go.com.
That's an EXTERNAL name, and is globally registered, so DNS will respond using the EXTERNAL address of the router, in my case, 96.226.xxxx.xxx.
My router is "smart" enough that, even though I'm trying to access an "external" address, my router will still re-route the packet back into my LAN according to the Port Forwarding rules defined either via UPnP or manually.
Finally, if the user's defined DNS server is NOT able to resolve that name for some reason, connection will ultimately fail.
So, in summary, there's three things that need to happen to connect correctly.
1- mDNS must work in the user's home environment.
To Test: On the iOS device itself, bring up a web browser and surf to the name of your device with a ".local" extension. For example: "BIGNAS3.local". If it works, you should see the web manager of your device.
2- DNS Resolution must be able to find your EXTERNAL name using YOUR DNS.
To Test: Well, you'll need to find out what that name IS. Easiest way to do that is to log into your drive via WD 2go from OUTSIDE your network using a PC, and note the URL.
Then, come back INSIDE your network, and do an nslookup on that name.
You need to make sure the address matches your OUTSIDE IP address on your router.
3- Finally, see if your router will do "Inside-Out-Inside" routing.
On your device's browser, browse to the EXTERNAL NAME of your device, with :443 at the end. Something like
If you get a response that begins with
Your browser sent a request that this server could not understand.
... then it works.