Everyone should hold off on upgrading to R090
+1 on the death of 5 GHz wifi after upgrading to R090
I have since downgraded back to 89 just now and 5 GHz is still not functional. All my devices see it as being able to connect, it just does not allow any data transmission, iPad says "Not Connected to the Internet," when connected to the 5 GHz band. 2.4 GHz still works as normal, fortunately.