If Samba sharing is too slow for you then you could try one of the Android FTP server apps.
There are several, and all the ones I've tested only work with wi-fi not ethernet (being primarily designed for phones).
Of the ones I've tested I'd recommend 'FTPServer - Andreas Liebig'. It will run in the background on the Q5 and I've got ~ 6MB/s speeds downloading from USB storage attached to Q5 to a PC running Filezilla.
Things to note are that I couldn't get it to work without setting an FTP password, I used port 2221, and Default Directory should be / so you can access attached storage at /mnt/sdb.