Why when I log into my MT router with atheros 5211 chipset (an 802.11a/b/g card) and select anything with 802.11g mixed or not does it not list the available frequencies? I can’t even enter the frequency I want through winbox.. Is this just not supported via Winbox, I’ve yet to try and do this from the command-line.. I might try that.
We use many 5211 cards (dlink ab520), butthey does not support 802.11g. I see the list at mode, but if I select 802.11g, the answer is that not supported.
I have a strange thing to 
i have a Atheros 5212 (CM9 Clone) it is a A, B , G card but its shows up in MT only like a B, G card..it will not give me any frequenses on 5 Ghz… i have mailed the support about this.
The 5211 never supported ‘g.’ It is only a/b.
For the 5212, be sure to send the supout file along with all the model/part numbers on the actual card you have.
John