Dan wrote:

Cheers Paul,

the zip file contains only the firmware
RT-N66U_3.0.0.4_380_3264-g79f6bde.trx and no readme. By your
description I cannot use the update for my UK rtn66u. So what can I do
then?

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

Try setting the OS to "Others". In the picture
here, I'm seeing a few more firmwares.

http://s32.postimg.org/v1u5w9cqt/others.gif

I got the hint from this FAQ page (noticed while
I was wandering around in there). Since there are
so many FAQs, it takes persistence to find anything
really interesting.

http://www.asus.com/support/FAQ/1010600/

There is even source code (implying the software
base is FOSS and the GPL says the source must
be released if it is used).

But I still don't know how the country-specifics
are handled. The release notes don't seem to mention
it.

Paul