John can you tell us what those results actually mean. Also what is the #a command and what does it do for the N66U ?
I'll try my best....
When the wireless hardware is initialized, it loads country and regulatory domain information that defines what the allowed maximum power level and available channels are for where the router is located. These are supposed to be based on the gov't regulations for that area. The stock firmware uses country codes US and EU and a couple of different domain values based on the router (there's one exception for a single release of the AC66). The domain is a number from 0-??. Hence the US/2 for example (country US, domain 2) in the output that was posted.
There is also a '#a' country code that is defined in the firmware. My belief is that this a test mode country code that was accidently left active. What #a does is set the allowed power level to it's maximum (316mW, when you add the antenna gain, the max transmitted power is 1W), and makes available for use all the channels that have been defined for a particular band worldwide. Note that unlocking all the channels really doesn't do anything unless your clients can also support them (they have their own country/regulations loaded as well). There have been posts on how enable the #a country on the router by entering a series of nvram set commands.
So, #a allows you to increase the power. The other reason a lot of people in the EU want to use #a is that the EU domain in a lot of cases doesn't match the channels that are authorized for a particular EU country (it's really a hodpodge of regulation, and the EU country code is basically the lowest common denominator).
Now, with those commands I was looking to verify what I have seen in the code in preparation for the next release. I was hoping that the 'wl txpwr' commands behaved differently on the N66 vs the AC arm-based routers and would tell me the actual power level (what it is telling you is the design spec max - not what is actually implemented in the router hw). The arm routers have a command for this 'wl txpwr_target_max', but it's not implemented on the non-arm designs.
Having looked at the code, this is how I believe things are implemented today in the fork without any nvram mods....
For all routers
OTHER THAN the N66, the power value entered in the gui will let you decrease power levels, but not increase them (the regulatory domains override the power value and it looks like the default value is at least the regulatory max)....you can set it higher, but it doesn't matter.
The N66U is a special case, and is partially unlocked. For example, the fork code changes the default US codes from US/39, Q2/2 to US/2, Q2/0 which based on what I can see on the arm routers should increase the available power (make the entered power value really work without any nvram mods). Unfortunately, I can't absolutely verify this because of the disabled command I mentioned before. I don't believe there is any change in the available channels though. This is the old 'Engineering Mode' (EM builds) option which never got removed on the N66.
