How to set up a Zyxel switch and restore file sharing

Hello everyone,

I have experienced above 10 years on web development but right now I am at networking and I am new here…

I have set up 8 computers and 3 printers using a Zyxel 24 Port Gigabit Switch (GS1900-24E). The system works and all was well until the last Windows 10 Pro update. The 7 computers (all running Windows 10 Pro) get files from the “main” computer. But now I can’t able to share my files over the network and it displays my warning. “Enter network credentials”. The “main” computer does not have any issues so I don’t know how to restore the file sharing.

And I have a few questions which are surrounding…

  1. What is the proper way of setting up this Zyxel switch, I assume the pros do not use plug-and-play?
    All the machines are running Avast Premier, can I add firewall/antivirus software to the Zyxel switch itself?
    How do I restore the file-sharing?

So I need help …
Thank you