With Windows Server 2012 comes WSUS version 6. In the WSUS Deployment Guide for Windows Server 2012, attentive readers will notice a critical change to the historical WSUS deployment strategy: "By default, in Windows Server 2012, WSUS [v6] uses port 8530. However, WSUS 3.0 uses port 80, by default." This might seem like a trivial detail to some, but if you're not careful when you're configuring your WSUS server in Windows Server 2012, you're likely to configure a server that no clients can find.
When you configure computers in your network to get their updates from a WSUS server, you provide the clients the URL for the WSUS server in a local/group policy setting. In the past, it's been sufficient to just use something like http://wsusServer since all URLs use port 80 if the URL doesn't specify anything different. This worked just fine with WSUS v3 and earlier; but now, if you don't change the default port when you configure WSUS on Windows Server 2012, you have to specify port 8530 in the URL your clients use: http://wsusServer:8530
If you neglect to change the WSUS port in either the server settings or the client URLs, your clients simply won't be able to find the new WSUS server. They'll get a 404 error, just like they would if they were trying to access a web page that's not available. What's more, if you use a third-party WSUS patch management, WSUS patching tool like SolarWinds Patch Manager, that tool won't be able to find the new server either. So, when you start testing Windows Server 2012 in your patching environment, be sure to configure the appropriate port to ensure everything plays nicely together. Patch management simplified!
For additional information about the implications of not specifying the correct WSUS port when using Patch Manager, see "WSUS v6 installs to port 8530 by default" on the SolarWinds knowledge base.