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New Member

Clients poor performance on Wireless

Hello All,

I am stuck on this issue with users reporting poor performance on the Wireless.

I've tested with a few devices and I see drop packets randomly, some mobile apps timeout but works when you refresh, Cisco Anyconnect reconnects randomly and frequently.

I've ran debug client xxxxx - I don't see anything .
Wireshark on client - I can see VPN reconnecting - 

When VPN disconnects the Wireless signal is full running at 144Mbps

Checked WLC 5508 ( - nothing wierd going on. I've even failed over the WLC to the standby one, no difference.
The SSID is Guest - Open security.


Any ideas guys? Or things to run to help to solve this wierd issue?


Everyone's tags (3)
VIP Purple

First of all upgrade your WLC

First of all upgrade your WLC code to stable verion in 7.4.x train. I would recommend to go for 7.4MR3 to be come out shortly.

The code you are running is the first release of 7.4  & above is 3rd maitenance release of that code.




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New Member

Hi Rasika,I will upgrade the

Hi Rasika,

I will upgrade the code to 7.4.121 since it is Cisco's AssureWave. I will also update FUS 1.7 this weekend and will let you know.

You think this will resolve the issue?



VIP Purple

HiFUS is the latest &


FUS is the latest & go for it. Keep in mind this FUS upgrade proces will take 30-40min & make sure you get enough downtime to do this.

Regarding your issue, I hope will fix it, even if not you are in better position as it has lot of other bug fixed in that code that you should not hit with that.

Keep us updated




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New Member

where you able to solve this?

where you able to solve this? 

if not: another thing to consider:

How many clients are doing high traffic on your WLAN? If you say that you have 4gbits connected, you do know that you do NOT have 4 gb for the clients available? When I was testing the 5508 - with all eight ports connected as a LAG and with vlan trunks, you could get about 3.5 Gbit/s of performance through the device. Through the device is actually what it is all about. All the traffic gets sent to the WLC, and the WLC then dumps it into the Network. All the CAPWAP Controll traffic also goes through this connection. So under ideal circumstances you have about 1/3 of 4Gbit for actual client traffic. You might want to try flex connect mode for high density areas, as the traffic can be "dumped" directly into the network at the ap.. 

If you have a lot of clients doing more then surfing the web, you performance problem might be the WLC itself! 


New Member

Hey, When you say that there



When you say that there is slow performance, there are multiple factors to consider


client <- AIR->   AP  <---> WLC  <---> core switch <---> wired network


First part to check is the client to AP perfomance (AIR):

Do you have good RF environment?

Do you have interferance? Noise?

What is the channel utilization?

Do you have WMM clients ? is it enabled?


Second part to check (Wired)

Do you have correect QoS confgiruations?

Do you have high speed LAN inside your network? If you connect wired client to access port does it work fine?


Thirs part to check (Core switch to WLC)

Do you have LAG enabled? Or do you use seprate ports for VLANs/WLANs ? 

Make sure it is not a bottolneck and the traffic is flowing smoothly.


About the WLC code, you are running deferred code but it  is still supported by the TAC.  Also upgrading the code is not related to the perfomenace in any possible way.




New Member

Hello,  Thank you for the



Thank you for the info.

I have upgraded to including FUS 1.7 and did not resolve the issue.
I also enabled LAG, now we have 4 ports (4Gb) into the Core switches.

There's no QoS configured on the switches, just default settings. 
I tested the LAN, works like a treat no performance issues at all.

When the issues happen this is what I see:
- Webpages not loading - timeout 
- mobile apps - not loading
- VPN - reconnecting
- ping packets - drop packets to default gateway (ASA firewall)

I've opened a TAC call but so far nothing concrete :(

New Member

I would vote for the RF issue

I would vote for the RF issue then .... do you face the problem with 2.4 GHz only? Particular places in the network? Some APs rather than others? Finding the answer for such questions will help you tshoot with the tac Good luck, Nour
New Member

The issue is happening

The issue is happening everywhere around the building.

For troubleshooting I left a spare AP in a comms room. I'm sure there's no RF frequency in the room! Again I still experience the drop outs in VPN, etc.

It happens on both 1602 and 2602 APs



New Member

Can you post the output of

Can you post the output of debug client xx:xx:xx:xx:xx:xx? Is there nothing coming by at all?

Capture a full association and output before, during, and after the issue. (connect to the wireless, do normal traffic, disconnect from wireless)

Also, post the output for show client detail xx:xx:xx:xx:xx:xx

To rule out anything non-wireless related, are you able to connect to the same VLAN on a wire and test performance?