Scan greather than 150dpi problem

Hi folks!
I have installed OpenWrt on my NETGEAR DGN3500 router, and I have a usb printer Samsung SCX-3405F.
I have installed saned ecc and it works!
But if I select a resolution greater than 150dpi page result first half ok, but remaining half all black.
I suppose not enough space on router for store temporary image file. It exists an hack to redirect temporary directory to another directory? Or how i can resolve this problem?

Thank you.

@pantpra, welcome to the community!

Swap space?

Doing a quick calculation here using A4 sized paper at 300 dpi, it's possible: