This probably wont’ be any good to most of my usual readers, but it’s a good tip for when sorting out issue’s.
When you change the IP of a HP 3992 MFP, you will need to install an app to recognise the printer has changed IP address for the HP scanning software to work.
You can download it from the HP support page for the printer, under the utilities section – HP LaserJet Fix Scan Utility
Install, then it will recognise the printer and do the changes to allow the scanning utility to work again.
Hope this helps anyone looking for a fix.