If you still thinking that Skype for Business is already dead, Microsoft is telling you the contrary, they are still improving their tools to do their best.
One of this, is that they had improved SaRA, this tool allows to fix many problems or at least it indicates you how to fix them.
The most important thing here, is that has been added support for Skype for Business. If you want to dig deepper in this tool, you can find more information in the following post: SaRA