Canopy AN500 - Unable to access AP directly

Hi guys, we are trying to configure an AN500 AP to SM link which was set up by the previous owner. 

Connecting to the SM directly, we can obtain an IP address from the upstream router, and we can ping the router albeit very (very) slowly (between 4000 and 16000 ms response time (ping times out unless we put a -w 100000 on it!!)

Now we want to connect to the AP directly so that we can configure it via the web interface on the internal IP (   The AP gives the laptop an IP address on the 169.254.x.x network with a Class B ( subnet mask - so we are confident that we are connected to AP.

When we try and ping the AP, it gives us a Destination Host Unreachable - we're connected directly so not sure where to go next..  Clearly the web page won't load unless we can ping it first.

Any thoughts on where we might go next?