http://technet.microsoft.com/en-us/library/cc708627 is targeted at older versions of WSUS. Older WSUS runs on port 80 by default, port 8530 if you set that.
You're running WS2012 (or perhaps WS2012R2), which runs on port 8530 by default, so make sure you are checking for the webservices on the correct port for your installation. You can check your current configuration on the WSUS, in the IIS settings.
When clients communicate with WSUS, there is no relationship to communication between WSUS and MSFT (each is a separate set of communication).
i.e. Client -> WSUS is one conversation, and, WSUS -> MSFT is a different conversation.
So, your WSUS could be happily contacting MSFT for data, even if the clients can't properly contact your WSUS.
On the client, check windowsupdate.log. This is the primary source of diagnostic information on a client.
On the WSUS, there are logfiles at c:\program files\update services\, but these are mainly for WSUS > MSFT comms.
You can check the IIS logfiles on the WSUS to see what client > WSUS comms are going on.
If your clients are 32bit, the WSUS Client Diagnostic Tool might be helpful. This tool doesn't work on 64bit clients. The Solarwinds client diag tool works for 64bit clients.
When you check the windowsupdate.log on clients, it's often useful to take a checkpoint of the file, at the point where the WU service started, because a bunch of useful info is echoed into the log at service startup.
What you can do, is to stop the AU service on the client, rename the windowsupdate.log, then restart the AU service, which creates a fresh logfile at service startup. Check that the logfile is showing the correct/expected configuration (e.g. that it's configured
correctly for your WSUS, and not pointing off to some other server or incorrect config). Walk through the logfile looking for errors, warnings, etc.
It's helpful to compare a problem logfile, with a "known good" logfile, unless you are very familiar with what "normal" logfiles look like in the environment you're working in.