802.11ac Clients on lighweight Access Points only connect at 86 Mbps

[fperez001111]

Dear Cisco community,

I am configuring and testing a WLC 5508 to change my autonomous access points to a centralized model. However, during testing on a cisco 2702i lightweight AP in an almost WIFI sterile room, my clients always connect at 86 Mbps no matter what. I already configured the channel width to 40 Mhz on the DCA menu and I am using a laptop to run some test. Curious thing, I have the same Cisco 2702i working in autonomous mode and the same laptop connects at 200 Mbps to it, so it seems that the RF parameters in the WLC are not configured properly for the 5 Ghz radios. Both access points are the same model, but the autonomous one have a way better performance on 802.11ac than the lighweight.

WLC firmware version 8.3

lightweigth access firmware ap3g2-k9w8-tar.153-3.JI3

Thanks in advance for any advice.

[Haydn Andrews]

First thing, are any APs working with that client on the WLC, 

Have you have confirmed the client is connected to that AP from the WLC?

If so couple of things to check on the WLC

• Ensure 802.11ac is enabled - Wireless> 802.11a/n/ac>High Throughput (802.11n/ac). Make sure the ac BOX is ticked, and all basically all other boxes on that page are ticked.
• SSID enable WMM and WPA2 

If that is all done, then you would need to do an over the air packet capture to see what the AP is advising is available data rates, and what the client is saying it supports.

[fperez001111]

Thanks for answering, In the High throughput menu I activated the SS4 (so now, ss1 to ss4 is activated). I also checked the WMM feature and it is allowed in all the WLANS, after that I restarted the AP. However, the problem remains. I tried to do a packet capture with wireshark while I performed a disconnet-connect process but I can´t see any "negotiation packets" between the AP and the laptop.

[Leo Laohoo]

What is the complete model number of the wireless NIC? 86 Mbps tells me the wireless is only 1x1:1.

[fperez001111]

Thanks for answering. Yes it is an Intel Dual Band AC 3165, an 1x1 card. However, this card connects to 200 Mbps to an autonomous AP, while the same card connects to 86 Mbps on a lighweight AP (even bot APs are the same model, 2702i, the only difference is the operation mode in the APs, autonomous vs lighweight), so the spatial stream limitation in the network card is not the issue.

[Leo Laohoo]

What firmware is the wireless NIC driver running on?  

When experiencing this "slow connection", what radio did the AP detect the card?  2.4 Ghz or 5.0 Ghz? 

[fperez001111]

It is working in the 5 GHz band in the controller panel.

[fperez001111 · Accepted solution]

DCA is not working

Finally I found the problem, Dynamic Channel Assigment (DCA) is not working at all. Despite configuring DCA and RF profiles to 40 MHz channels on the 5 GHz band, the AP was working on 20 MHz. I found the same problem in this topic: https://community.cisco.com/t5/other-wireless-mobility-subjects/global-change-to-40-mhz-channel-width/td-p/2616239

The only solution I found is to set manually the channel and the channel width. Multiple restarts on the 802.11ac interface or WLC reboots does not help at all. If anyone have the same problem, go to Wireless / Radios / 802.11a/n/ac and in the correspondig AP go to the dropdown menu at the end of the row, choose Configure and change the channel assigment to Custom, channel width to 40 MHz and choose and appropiate channel. Seems to be a bug on the WLC firmware version 8.3.

Thanks a lot to everyone who answered this post.