WNDR4300 v1? setup as access point

I have tried http://kb.netgear.com/app/answers/detail/a_id/19852 which sets it up as an AP without using the Internet Port, as well as the "Wireless AP" under "Advanced Setup", and as (poorly) documented in the manual, which does use the Internet Port. I am assigning it a fixed IP address and have set the main router to give it that address. I have the same problem (no wireless internet access on only a Windows 8.1 laptop) either way. And, I may be getting senile, but I swear it worked before - it is installed in a second home and I first installed it last fall, then was gone for several months and returned without making any changes and now have this problem. The only difference that I can think might be responsible is that the laptop was upgraded from Win 8 to 8.1 while I was away. Let me explain further.

The setup is a different brand router upstairs which is used for both wired and wireless connections. The WNDR4300 is installed downstairs and configured as an AP to provide a better signal using the same wired/wireless network configuration as the upstairs router. It successfully works that way with Win 7 laptops, an iPad and a couple of Google Nexus 4 phones. The Win 8.1 laptop works wireless with the upstairs router and it works wired to both routers. The only problem is no internet access when connected wireless downstairs. It is my main laptop.

Any ideas/help appreciated.