@Gertjan:
@Waqar.UK:
I understand, the Asus is in the front line.
Also, why I cannot connect my pfsense box to my wan port instead of lan port?
Where did you hook up this Asus box (the AP) ?
I understood : on the pfSense LAN - as one of the devices on your LAN - like PC's, printers, etc.
It's an AP, thus that is where it belongs.
On the pfSense WAN side you have tour "ISP" box (also a router), that's it.
pfsense LAN port to Asus.