unwanted client isolation AR9280 @ 5GHz mode

[Gertjan Hofman]

Apologies if this should go to the ath mailing list, but we are not sure where in the stack the problem lies.

On a 3.11 kernel, we are trying to create a AP host using the following  hardware: driver (usb) ath9k_htc: Atheros AR9280 Rev:2 using htc_7010.fw firmware  (1.3, extracted from debian unstable)   After solving some  regulatory domain issues by patching the ath driver, we can force the card into becoming master at 5 GHz.  However, at  5GHz, the clients are isolated from each other (can not ping etc).  When we switch back  to 2.4 GHz (making only two changes in the hostapd file, hw_mode=a->g, channel=36->1) the system works as expected.  


Using wireshark/tcpdump I verified that ARP packets are _not_  transmitted from the AP host to other clients. In other words, ARP from  client to AP hosts are resolved ok, but a client trying to resolve the  MAC from another client gets no response and the packet is not seen even on a Windows host running wireshark.  Switch to 2.4 GHz and the ARP packets return.


Looking at mac80211/cfg.c, I see that host isolation is indeed an option.  I  printed the value of IEEE80211_SDATA_DONT_BRIDGE_PACKETS but it is  false as expected. 


Can anyone tell me whether this is likely a problem at the mac80211 levelor the firmware ? Are there other settings that kick in a 5  GHz that would not at 2.4 GHz ?

We are quite capable of modifying drivers but have little knowledge of  wireless hardware.  Any information would be much appreciated.


Sincerely,

Gertjan


hostapd (v1.1) settings are:
interface=wlan0
driver=nl80211
ssid=MSS-01
ieee80211n=1
macaddr_acl=0
auth_algs=1
ignore_broadcast_ssid=1
require_ht=1
ht_capab=[HT40+][SHORT-GI-40][TXSTBC][RXSTBC123]
wmm_enabled=1
hw_mode=a
channel=36
country_code=US
ap_isolate=0