What Wifi USB adaptors could work in __ap and station mode at once

Question

I followed these instructions and still can't get AP working on the same interface. I have these devices:

Ralink corp. RT3060 Wireless 802.11n 1T/1R is giving me an error:

RTNETLINK answers: No buffer space available

Linksys WUSB600N v2 Dual-Band Wireless-N Network Adapter [Ralink RT3572] (USB wifi adaptor):

RTNETLINK answers: Device or resource busy

these errors occur when I start second virtual interface on the same wifi device. What wifi adaptors support two virtual interfaces? What should I look for in hardware specifications? Maybe there are already known USB wifi adaptors that could work as AP and uplink at once?

Answer 1

On Linux, you can verify if (and under what conditions) your adapter supports simultaneous STA and AP operation by examining the output of

iw phy<n> info

where n is the number of your adapter, e.g. phy0.

In the output, there is a section called valid interface combinations; here is an example of an adapter that supports simultaneous STA and AP operation, but only on the same channel and using an equal broadcast interval:

[...]
valid interface combinations:
     * #{ managed } <= 1, #{ AP } <= 1,
       total <= 2, #channels <= 1, STA/AP BI must match
     * #{ managed } <= 2,
       total <= 2, #channels <= 1
[....]