EX6130 extender keeps diconnecting from router

I have a problem with a brand new Netgear EX6130 range extender.... I have read other posts and tried all the solutions (I think).

Th internet facing rounter is a Livebox 4 provided by Orange telecom. It's in the same room as the extender and my laptop. All within 4 meters of each other. The extender has latest firmware.

I have configured the extender multiple times, using WPS and the browser interface, and the outome is SUCCESS! I connect through the extender and access the internet and all is well for a few minutes then the router light goes off and connection is dropped. After a few minutes the light comes back on for approx 5 seconds and then off again. That cycle repeats but never returns to a working state. Using the router's list of connected devices I see the extender then it sudenly disappears. There doesn't appear to an error log on the extender or the router unfortunately.

Other devices connected to the router directly via WIFI maintain connection with no signal drop (Youtube running on the TV to test).

Can any help or do I return the extender to Amazon?

Thanks.