Main router works, extender is all green but shows no internet connection

I purchased this extender about 6 months ago, it's been working fine until yesterday.  My main router (also Netgear) is working fine with internet connection but now when I connect to the extender it shows "no internet connection" even though all of the lights are green.  I've tried restarting my computer, unplugging the routers and the extender, nothing works.  What could  have happened all of a sudden to make it do this?