Around 1/9/19, Microsoft pushed a Windows update (KB4480970) that breaks SMB in a way that inhibits network communication with the computer’s shares. This is most often reported as sudden inability to scan to shared folders from a network-connected scanner.

A subsequent patch (KB4487345) was released on 1/11/19 to correct this and it can be found here (choose your platform):

http://www.catalog.update.microsoft.com/Search.aspx?q=KB4487345