I am not a Windows guy, but what I would try is to see if you can access the drive when attached to a PC as it may be the drive. Be sure the router firmware is up to date. Check the settings in the router for the USB drive. Power cycle the router and the PC after any changes to either as that sometimes helps.

@tomscot2 

 

Why still on 1903?

 

Check your Windows Update, 20H2 is the latest version.

 

There does seem to be a 'bug' in the Update list, you'll see Optional Updates, and those appear as Driver updates. DON'T take them, they are really backlevel and could cause problems (just Google "windows update optional updates drivers very old" and you'll see a lot of warnings not to do that).

 

This link describes a fairly recent change to the Driver Update list, https://redmondmag.com/articles/2020/10/29/windows-10-optional-driver-updates.aspx, and it did reduce my list of d/l's. However, I'd still stay away from those unless you know the file WILL HELP.

 

Here is one of the many links about the issue, https://www.windowslatest.com/2020/09/29/dont-use-windows-10s-optional-updates-for-stable-system/.

 

I do NOT have a problem accessing the router external drive.

 

Have you take the drive to a PC and run CHKDSK on it, or even tried to write to it on a PC?

 

Also, as suggested above, have you tried using NET USE to the share and assign a drive letter to it and then see if you can write to it? If you can, it might be a permissions problem?

@IrvSp 

 

I updated to the latest Windows 20H2. The problem  remained. I fixed with the steps my previouse post marked Best Solution. I had to this on all three of my computers on my home network.

 

tomscot2 wrote

@IrvSp 

 

I updated to the latest Windows 20H2. The problem  remained. I fixed with the steps my previouse post marked Best Solution. I had to this on all three of my computers on my home network.

@tomscot2 

 

That 'problem' was NOT new on V1903, rather SMBv1 was not installed by default in Windows 10 Fall Creators Update(1709).  

 

No version past V1709 removed it on install. Some would remove SMB1 if not used for a period of time. Don't know why you had to re-install it unless this was an update from Win8 with V1903, then this could of happened?