I have four of these (C2 v1) acting as dumb AP's. I have been experimenting with both early OpenWRT port and (recently) LEDE port " LEDE Reboot 17.01-SNAPSHOT r3889-a0af7c8c59 / LuCI lede-17.01 branch (git-18.098.72829-575e327)". Routers work fine but have issue with buggy 2.4GHz support.
As soon as there is lot's of traffic on 2.4GHz, kernel will start writing "phy0: rt2x00queue_write_tx_frame: Error - Dropping frame due to full tx queue" into log and traffic will stop.
And it will stop in worst possible way: device will still be connected to AP but no packets will be able to flow so it will not jump to another available AP but just hand on to one that hang!
I can crash them at will by streaming particularly heavy DLNA stream to VLC on my iPhone using 2.4GHz.
So currently Archer C2 is only usable in 5GHz band under OpenWRT or LEDE. At least that is my experience. If there is newer firmware, do tell.