Hi Koen,
Thanks for your feedback. To be clear on this, I've attached a pic of the external antenna, having 3 connectors. Given that the AP-274 has 6 N-Type connectors in total:
2G0, 2G1, 2G2
5G0, 5G1, 5G2
So we would have to connect each of the following connectors to the 2G0, 2G1, 2G2 ports for the antenna doing 2,4Ghz. And we should connect another antenna to the 5G0, 5G1, 5G2 ports?