Nexto OTG supports standard [mass storage class] and [PTP(Image) class].
So if your D50 supports standard mass storage class, then you can connect to ND2300 now.
You have to check if your D50 supports mass storage class first.
Connect your D50 with mass storage mode to PC.
Then open the [device manager] of XP. Check if [mass storage device] appears in the [Universal Serial Bus Controller] tab.

According to our experience, Nikon or Canon's PC connection mode is not mass storage class. It needs their proprietary class driver wich is provided with the Camera. They do this way because they want to enable user 'Remote capture' or etc, but with standard way, they cannot do it.

So if they do thing in proprietary way, then we cannot support it because we don't know how they works.

Hi, thanks for your reply. My Nikon D50 comes up as a compatible mass storage device under XP. Recognised by my computer and can be used this way.

When I plug it into the ND2300(xpress) it detects the USB, but returns an error message 'Unsupported USB! Code 0x0001'. If I plug it in in PTP mode it is recognised and can copy, but I'd prefer Mass Storage mode. Any further suggestions?

Thanks

0x0001 error means just fail.
We can check this case by sending trial firmware to you.
So pls, send me e-mail. We can support you.
If you like it Send to hajason@nextodi.com