So how would that work on Attitude Adjustment? Since changes in the way regulatory database is used, the older regulatory.bin hack doesn't work.
Also those two channels were working for me on some versions of DD-WRT (but I forgot which ones). Maybe we should take a look at how they solved the problem.
The limits seem to be applied incrementally - if you have a country "00" or "US" which does not allow ch12+13 but 500mW, in whole europe you would be able to legally use ch1-13 but no more than 100mW - setting the country to "DE", you will end up with ch1-11 and 100mW.
I needed ch13 in one 1043nd, for this one I had to completely open country 00 and US, created a country "UX" which matches the US regulations. This way I can set country "DE" and get the correct limits (ch1-13, 100mW). To match the original US limits I need to set the country to "UX".
This is of course no solution for openwrt, if TP-Link fails to set the country code in their products.
Also did anyone check how things work in the official TP-LINK image? I've heard reports from people that on stock firmware those channels work, but I didn't check that out yet myself.
Yes, you can enable any channel in the stock firmware, so the openwrt image is by far more FCC-Compliant than the original firmware.
I dont know the reasons for the switch to the "internal regdb" in openwrt, because the images distributed before also followed those FCC rules if the user of the firmware did not break them intentionally. But i am not a lawyer - and for whatever reason this has been done, I am quite sure it was *not* done to spoon-feed the users. If anyone could come up with a solution to modify the flash to set the right local country code this would be nice. Unfortunately this is beyond my knowledge.
Otherwise you only have the one option to compile your own image in order to overcome the channel-limit.