Be careful of recent update KB4480970 on servers. This Microsoft update stopped one of our customers from accessing all the shared drives on the server. When they tried to access the mapped drive or browse to the server they got an error message "The handle is invalid".
Uninstalling Microsoft Update KB4480970 from the server resolved this issue. (We had also previously uninstalled KB4480055 - we don't think this caused the issue, but just in case it is a combination of both updates, you may need to hide both.)
We are going to temporarily hide this update on our customers servers. To hide it you first have to download it.
Go into Windows Updates and select View update history. Right click on the update and select Hide update. This will ensure it is not installed. Note it is easy to unhide this update and install it at a later date.