Windows 7: Network drive stopped copying files

I was copying a large folder (with about 300 subfolders) from a USB drive plugged into my desktop to a USB drive plugged into our Asus RT-N66U router. After about 1/2 the files were copied I got a window pop up "Destination Folder Access Denied". This is after about 26 GB of photos had been copied out of 44 GB.

I think, that's weird... no amount of clicking Retry has any effect.

I right click on the folder, click Properties. Attributes show as Read-only. I unclick Read-only, hit Apply, after 3 minutes it finishes, now the Read-only is clear. Try copy files again, get the same error, cancel, go back to Properties and the Attribute on the properties screen is back to Read-only.

So I look at Security. Ah, here's the problem, nobody has permissions! So I click edit, Everyone, Allow Full control, Apply. Popup screen says "Setting security information on..." and then all the checkmarks on the permissions disappear. So it didn't work.

I go back to the Security tab, click advanced. Permissions show Special for all entries, top folder only. I click on Everyone, click Edit, and change "Apply to" to "This folder, subfolders and files" (all permissions). Click apply, popup says "Setting security information on..." and then the Advanced Security Settings goes back to "Special". Nothing changed.

I click Owner. Here's the issue! Current owner is admin (RT-N66U\admin). I click edit, select Mark (Mark-Desktop\Mark) which is me with full admin privileges etc, click apply and I get a popup with a red x "Windows Security- Unable to set new owner on Laura Photos" (that's the folder name on the external drive).

What the heck can I do now?

Mark

To be clear its the usb thats giving the error is it formatted ntfs?

Yes it is. I found a workaround- I dismounted the drive from the router and plugged it straight into my Desktop. There were no permission errors that way. Copying went a lot faster too...

Have not finished with the tasks I need to perform, but when I am I will plug it back into the router and we'll see what happens.

Use built in robocopy it's the fastest way to copy files just type at a cmd prompt robocopy or you can download a GUI for it

What I've found with USB mounted drives attached to Routers is that you need Share the drive, when logged into the router, with permissions set for a Router user, usually this would be the Admin user but most routers will allow you to set shares that are allocated to a separate user or users and these user name(s) would be used when creating a Mount Point for the network drive, they are not the same users as those on the system itself even if the names are identical. These Router Rights are used to access the drive and then the NTFS permissions take over for full access

You still need to set the correct NTFS permissions on the drive, (as you would with the normal SATA drive), but regular system admin rights can fail when permissions on sharing the remote drive clash

It may explain your issues or at least act as a starting point.