@Cellcom, please provide more information.

What kind of antennas has the »Netgear WISP device«? Directional antennas as the CPE510 has or omnidirectional antennas typical WiFi routers have?

And what's the distance between the two devices?

Also, »AP« mode for the CPE510 is wrong if your »Netgear WISP device« operates in AP mode already.

You would use »AP Client Router« mode for a CPE510 connecting wirelessly to a WISP base station, routing a private LAN to the WAN, providing firewalling and DHCP services etc.:

@Cellcom, usually you have to ensure a minimum distance of about 10m for a CPE with free line of sight if used with standard clients with omni antennas. You could also try to reduce the Tx power of the CPE. Anyway, the range will be very limited for a device using omni antennas, it will be between 10m and 100m only.

Cellcom wrote

As long as LOS is concerned, the WISP client i.e. Netgear Site Survey clearly show the recieving signals' strength

This means nothing. You can see the CPE's SSID on standard home APs over a distance as large as 600m, but you won't be able to connect the AP to the CPE over such a distance since the AP can't send anything back to the CPE.

CPEs are designed for PtP links between two CPEs over a distance of some kilometers. Their beam is very narrow to achieve a high RF energy over such distances.

You can imagine it like a lighthouse: a lighthouse focuses its light to guide the way for distant ships. A CPE does the same with its WiFi signal. Thus the name »Pharos«, b/c »Pharos of Alexandria« was the world's first lighthouse in history.

With an omnidirectional AP you are on a ship which has a standard light bulb that illuminates the surrounding area of a few meters only, but now all around (360º), not in a certain direction. You can easily see the much brighter (bundled) light signal from the lighhouse on your ship over big distances.

And now imagine the distance your ship must have to the lighthouse for the lighthouse keeper to see the weak light of your light bulb. If you are too close, he will see only the lighthouse's own bright light overloading the weak light bulb. If you are too far away, he won't see your light bulb either, b/c it's much to weak to see its light over a long distance.

This, a lighthouse and a light bulb, is the situation with mixing a CPE with directional antennas and a device withomnidirectional antennas. It might work over a short (but not too short!) distance, but in general it's a very bad idea to use standard APs with a CPE.