Slow file transfers over USB

Official Hardware Mega GIGA R1 WiFi
1

I am attempting to transfer some files over USB.

I have one Giga R1 plugged into a camera via USB (the server r1), and another R1 with a USB flash drive attached (the client r1). The "client" R1 connects to the WifiAP of the server R1. Then the server R1 transmits the files on the camera to the "client" R1, which writes them to the USB stick.

The bottleneck is the read/write speed to the USB devices. (Transmitting an image over the wifi happens in seconds.)

When I connect the camera to my PC, I can transfer a 3mb file in just a few seconds. When I read the same file from the camera with the Giga R1 over USB, it takes around 2+ minutes.

Does anyone have any suggestions for how I can speed this up? I'm currently just connecting to the camera's USB drive as per the standard Arduino_USBHostMbed5 FileRead example. Once connected, I use fread and fwrite to deal with the files.

Thanks for any suggestions!

2

Update: It turns out that if I replace the camera with a USB flash drive, everything is pretty quick. So clearly it's something about this camera.

I wonder if it's negotiating a slower transfer rate with the Giga R1 than with the PC? And if so, I wonder why?