@jcouzy even that doesn't seem to work. The KPN TV boxes apparently require both an internet connection (vlan 6) and the IPTV connection (vlan 4) on the same cable. Using the iptv setting isolates...

@btx I've tried with the settings in the screenshot above, but no luck. Though I haven't found any documentation yet which might explain all these options. I just managed to break the dhcp server by...