Dan wrote:
I have looked at the UK asus rtn66u website, it no longer shows any
fimware update url. But the USA one at
http://www.asus.com/Networking/RTN66U/#support_Download
and to http://www.asus.com/Networking/RTN66...Desk_Download/
allows for firmware update, which trhe latest is
FW_RT_N66U_30043803264.ZIP

above url say that I can download from global, only my connection
speed matters but the file will be the same. Can I use the above named
zip file to update my rtn66u?

http://www.asus.com/Networking/RTN66...Desk_Download/

"Products certified by the Federal Communications Commission
and Industry Canada will be distributed in the United States
and Canada. Please visit the ASUS USA and ASUS Canada websites
for information about locally available products."

The firmware issued to you, should be by geolocation. The
web page should contain references to communications
bodies like OFCOM in the notes section (if the geolocation
figures out you are physically in the UK).

Channel allocation is slightly different around the world.
You have a channel 13 on your Wifi, and we don't here. The
license-free terms of usage are strictly defined by the
radio spectrum being used. If I brought your computer
here, and it was using channel 13, then I'd be in violation
of the DOC rules. Not that anyone would notice. I expect
accidental channel 13 usage happens all the time.

You could try looking inside the ZIP file, for any
README file that might say what countries it is for.

Paul