Slow connection on flex connect mode (virtual WLC 8.10.130.0)

[kyawhlawnmoe1]

Hi,

We have a virtual WLC with version 8.10.130.0 and two 3700 APs.

Both APs are connected to 3560 switch (12.2(55r)EX11) and they use flex connect mode.

It was working before and suddenly we are having a very slow wireless connection issue. We have checked the switch ports and changed the cables. Unfortunately, the issue is still there.

We have the configuration and looks good. Is there anywhere else we can check to solve this issue?

Thanks,

Moe

[ammahend]

you can try these steps since its a very generic question, capture a complete transaction of probes, 802.11 authentication, EAP, association (this you can capture over the air on channel AP is operating) then capture radius, dhcp, application traffic (this you can capture on AP and wlc ethernet port, span the ethernet port on AP and wlc on switch to another port with Wireshark connected in it). 

once collected add a column a custom column for delta time in wireshark and start by looking which transaction takes longer than usual, it will give you some idea what’s causing delay and where to focus your attention. 

it would be also be a good idea to run your config through WLC config analysis tool

most of the slowness issues are result of fragmentation, so make sure from source to destination where you are measuring slowness has no fragmentation, either allow jumbo frames end to end or keep mtu within 1500 by adjusting mss value along the path and see if it improves things for you.

[Rich R]

8.10.130.0 is very old!  Refer to TAC recommended link below - currently 8.10.190.0.
As @ammahend suggested use Config Analyzer (link below) to check your config.
Have you tried rebooting the APs and/or the WLC?
What else has changed?  Has there been an application change, has a certificate changed, did new neighbours move in and install a WiFi network using the same channels?  For that matter how are your APs selecting channels - DCA or you've assigned statically?  Are the clients on 2.4GHz or 5GHz channels?  Have you made sure clients are using very latest WiFi drivers?