WM3000RP won't connect to Access Point

Hi. I have a Netgear wn3000rp and won't connect to the Access Point.

My setup is a big strange, but cannot be avoided. I am using a standard router with static IP. That router is connected by cable to a Gemtek P520 Access Point quite far away. Thus, the router wifi feature is disabled since I use the wifi provided by the Access Point. My router's internal IP is 192.168.0.1 (static)

I can connect wirelessly to the AP with my computer USB network card, and I am able to connect with several mobile phones as well. No problem there.

The trouble is that when I place the Netgear wn3000rp and try to make it connect to the AP (following the guide instructions carefully), it fails. My AP internal address is 192.168.0.12 (static).

At the final step of the process, when everything was apparently going normally, tt says:
"The selected network is no longer available. Please make sure the existing network equipment is within the proximity of the Extender."

Distance is not a problem because I am at the same time, and from the same location, surfing the Net with my mobile phone.

The problem must be in some router configuration. While the AP is WDS-capable, I have not been able to use it, so I'll just ignore that and choose the non-WDS option. It doesn't work either. When I get the final error message "The selected network is no longer available", I can get into the Netgear Extender configuration and I see that the IP address there is 192.168.1.250 (defined automatically, it seems)
As I said, the AP is configured with a static internal IP address which is different in range: I have tried to change the band (g/b/auto) in the AP, passing from WEP to WPA or no password at all. I have tried to change the Netgear Extender address to a static address in the range of 192.168.0.x (and suitable submask and gateway), but to no avail. (By the way, what one should the gateway be, the IP of the router or the IP of the AP? I have tried both). I have even modified the TCP/IP V4 Propierties of the Wireless Connection in Windows configuring the IP, Gateway and DNS manually, but it does not work either. Any help? Where does the problem lie? The WM3000RP WON'T connect to the AP network, no matter what I try.
If I hadn't tried a million times, it would seem that they don't couple or the passwords were wrong... but I have entered them too many times. So why my Repeater won't connect to my AP? My phone, my computer, my android TV stick do!!!:mad:
For short, this is the configuration:
Router static IP: 192.168.0.1 (DNS desactivated)
AP static IP: 192.168.0.12 (these two are connected by cable) (DNS activated here)
My phone and PC will connect wirelessly to this AP regardless of Encrytion (WEP, WPA, etc) but my Netgear Extender will detect the network emitted by the AP, will try to connect to it in the setup, and then fail miserably.

I have tried everything, as I said, short of changing the static addresses in the router and the AP as those are not of my property (I am a guest) and don't want to mess too much.

Please help! I will be happy to support you with any extra info you may need.