Problem with a network drive

Hi,

I have an Ubuntu computer attached to my Windows 10 (1903) through a mapped drive (letter U). I use Synergy to access it using my windows keyboard and mouse. I use the drive on the Ubuntu computer for backups. Lately when I've tried to get into the U drive I get an error:

The funny thing is Synergy is still working just fine.

When I reboot I have no problem accessing that drive until I try to transfer a file then it happens again, not all the time but often.

How are you accessing it by name or IP?

I access it by clicking on the letter in File Explorer.

Does it show up with the name ok in explorer

Yes, if I understand what you are asking, it shows up no differently whether I can access it or not. The U drive is mapped to a folder on the Ubuntu computer named Backups. I've been using this system for several years without a problem, this just started happening today. The fact that Synergy works fine (through the LAN) is puzzling.