Hi Dennis. I'm Greg, an installation specialist and 9 year Windows MVP here to help you.
I'll give you everything possible to try for files sharing problems so at least something will work. If you need help performing any steps I am standing by here to help:
Go over these steps to make sure File Sharing is set up correctly: https://pureinfotech.com/setup-network-file-sha...
To troubleshoot sharing problems:
https://www.lifewire.com/troubleshooting-window...
https://windowsunplugged.blog/2018/03/27/networ...
https://www.thewindowsclub.com/network-computer...
https://superuser.com/questions/1202441/windows...
If Windows 7 is involved make sure if applicable you have the WIndows Update released to fix Windows 7 sharing issues here: https://www.bleepingcomputer.com/news/microsoft...
Test if turning off Controlled Folder access helps: https://www.thewindowsclub.com/controlled-folde...
You may want to change to sharing via OneDrive: https://www.computerworld.com/article/3256907/m...
I hope this helps. Feel free to ask back any questions and let us know how it goes. I will keep working with you until it's resolved.
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