Ok I solved it. I Basically did what was in the link i posted above.
Its as simpel as installing the avahi-dbus-daemon
Then add under [server] in /etc/avahi/avahi-daemon.conf:
allow-interfaces=br-lan,VPN,br-guest
add under [reflector]
enable-reflector=yes
Start it:
/etc/init .d /dbus start
/etc/init .d /dbus enable
/etc/init .d /avahi-daemon start
/etc/init .d /avahi-daemon enable
Add firewall rule for guest (VPN and lan already have access to router)
Then add firewall rule to access CUPS server from guest (VPN and lan already have acces):
