I have just bought a AEBS and all works on a 2.4Ghz network. I think I have set it up correctly. I can see my wireless network with 5Ghz in brackets in my Airport menu but I can't connect to it, just times out. I have read this seems to be a firmware issue for the AEBS on 7.5 I can't see in Airport Utility to set the Radio mode to 'N' only, I only have 2 options as shown in the attached. Any ideas?