This worked for me with Linux Mint 18 x64 with Brother mfcj870dw (mfc-j870dw) connected via WiFi DHCP
Downloaded the generic installer from Brother
http://support.brother.com/g/b/download ... w_us_eu_as
Installed, printer worked, scanner not.
Then downloaded the scanner drivers from the same page (driver, key tool, settings file)
http://support.brother.com/g/b/download ... _as&os=128
Then installed the packages using gui tool GDebi package installer and followed the instruction to set up the printer using static IP.
Checked the IP from rooter admin page.
brsaneconfig4 -a name=(name your device) model=(model name) ip=xx.xx.xx.xx
My /opt/brother/scanner/brscan4/brscanenetdevice4.cfg has this one line:
DEVICE=LaciScanner , "MFC-J870DW" , Unknown , IP-ADDRESS=192.168.10.107
I also created a symlink from /etc/udev/rules.d/40-brother-libsane-type1.rules to /lib/udev/rules.d/40-brother-libsane-type1.rules
However, I am not sure if this was necessary, but others mentioned the /lib/udev/rules.d/40-libsane.rules file so I thought the rule file from Brother should be linked here too.
added myself to the scanner group:
sudo usermod -a -G scanner laszlo
Then scanimage -L and scanimage --test worked fine as well as simple-scan. Tried as root first then the regular user.
This site helped me to figure out the problem with using my scanner, so I thought I put my results here too. It may help others.