I think that there is a bug on 2.9beta16. Sometimes the wlan card is lost. You have to restart the rotuer via /system reboot or unplug the power. After that the wlan card commes back. This is happening with RB500 and 5211 card. This is happening only with RB500 and 2.9beta16.
reg
Kujtim
ARTMOTION
I have the same problem but with AT5213 card.
Could you please write more specific on that problem, what did you do before rebooting or powering up the RB500 and it didn’t find the wireless card?
Could you send the support output file which is made when the wireless card isn’t reckognized? Send it to support@mikrotik.com
in the moments wlan card dosnt appear on the list I dont really have time to make an support output file 
. I had today similar problem when i;ve run Snoop. After that the wlan interfaces disappeared.
I had also this problem when I firstly booted the RB500, after I unpacked it.
Come on - producing the supout file is a matter of some seconds.
I admit that most of us are under pressure when systems don’t work and customers start calling you. But there’s only a chance that a bug get’s discovered, identified and fixed if we/you/anyone reports it back to MikroTik…