VDI plugin for Skype For Business 2016? Is it needed

You aren't the only one having this issue with some of the April updates not synchronizing with WSUS on Server 2012 (including KB2889923). The following workaround was posted by Microsoft and may work for you.

To work around this problem, use the following method to manually synchronize new updates in WSUS. Repeat these steps for every update category that you want to synchronize.

1. In the WSUS console, disable updates from synchronizing. To do this, follow these steps:

   • In the navigation pane, expand the node.
   • Click the Options node.
   • In the center pane, click Products and Classifications.
   • In the Products and Classifications dialog box, click the Classifications tab.
   • Clear the check box for the classification that you cannot synchronize to WSUS.
2. Run synchronization in WSUS. To do this, follow these steps:
   • In the navigation pane, expand the node.
   • Click the Synchronizations node.
   • In the right pane, click Synchronize now.
3. In the WSUS console, enable updates for synchronizing. To do this, return to the Classifications tab, and then select the check box for a classification that you want to synchronize.
4. Run synchronization in WSUS.
5. Repeat steps 1-4 for any other update classification that you want to synchronize, as appropriate.
   • Note You can enable and disable more than one update classification at a time. However, at least one classification most be enabled for WSUS synchronization to occur.
6. If System Center 2012 Configuration Manager (ConfigMgr) is present in the system, run synchronization in ConfigMgr.

It is a little hackish, but if you right click > copy the Join Skype Meeting url from the invite, paste it in your browser and add "?SL=1" (without the quotes, so it would look something like https://meet.yourdomain.com/user/98daf9w?SL=1) on the end, it will force to join in via the web app (where you can join as guest) instead of automatically opening Lync/S4B client that requires a login.

Hope this helps!