EX7000 Won't Connect to Certain Websites (AC1900 WiFi Range Extender)

A few months ago I updated my router (supplied by provider not Netgear) and suddenly I was unable to access most websites whenever I used the EX7000 as an extender.  Some could be accessed, while most, e.g. amazon, argos, etc., could not be accessed - responding with a dns error.  I trawled the internet and changed IP and DNS settings galore but to no avail.  Nothing was going through the EX7000 as an extender - not my iphones, PC, laptops, nothing.  Eventually I had to disconnect the EX7000 and leave it idle under the desk, just gathering dust.  I was sure that I'd never be any use to me with the new router, then I came accross this thread and the suggestion regarding the firmware.  I plugged the EX7000 back in, noted that my firmware was the most recent one 1.0.0.768 or something (must have updated it around the time I installed the new router), so I downloaded the previous firmware 1.0.0.66 and loaded it.  Bingo!  Everything is working a treat.  So, for me, the solution came from backtracking on the firmware.