@niels
Is the kerlink sending status packages? Probably not as that would make the gateway appear on the API page and on ttnstatus.org. (tcpdump will show packets with readable (in the ascii part text containing "{"stat"" if it is)
For status messages you should have (fake) GPS enabled in the configuration. (For fake you'll need to set the coordinates as well, but I think kerlink has real GPS??)