QNAP TS 101 as sane- server -problem

Hi all,

I had setup a QNAP TS-101 and run NetBSD 6.1 on it.

I want to use this device as scanner-server using sane and I made a 
working setup with a custom kernel.

My problem is, that the scanned images on my workstation are in a very 
poor quality... Not only if I use my workstation over a network 
connection...
The images I scanned with scanimage on the QNAP device are bad, too...

The scanner works perfectly if I use it directly attached on my workstation.

Do I have to use different settings in my kernel?

Here are my settings I added to the GENERIC kernel:

#USB Generic Driver
ugen* at uhub? port ?

#scanner
#uscanner* at uhub? port ?
usscanner* at uhub? port ?

Any ideas?

Greetings,
Helge