Wireless users - Teams Video call issues and internet issues

[sagarshaha]

Hi,
We are using Cisco 3500 Series Wireless Controller and around 10 units of C9115AXI-K wireless access points. Everything was working fine until last 2 weeks where users started complaining the internet is breaking, Teams call are getting disconnected or putting on hold and sometimes the wifi completely disconnects and connects after 10-15 secs. even the pings are issues. 
I have been breaking my head for past 10-15 days with all possible changes but cannot solve it. The only change I did was changing the DNS for end users...from ISP DNS to 1.1.1.1 and 8.8.8.8

Please help me with this issue as its causing major issues in the office.
My network. 
ISP (Leased line - 500mbps) -Connected to Sonicwall NSA2800 Firewall -> Uplink to Cisco 48 port C9200L-48PXG-4X (DHCP and DNS is on switch)- Wireless Access Points.

Spoke to Sonicwall support and they say, everything is good on firewall. Its the network devices having issues,
Wondering if the DNS is causing issue or any compatibility issues ?

Appreciate if you experts can give me some lead that where we might be missing out.
Thank You!

[Mark Elsen]

    - @sagarshaha                    1) Such issues such as suddenly during the last 2 weeks ; are suspicious and could
                                                   be related to resource exhaustion on the wireless controller : Reboot it

                                               2) Aireos platforms are getting old and outdated and should use last  release
                                                   available : : https://software.cisco.com/download/home/286312601/type/280926587/release/8.10.196.0

                                               3)  The mentioned access point models will work better with the new 9800 controller
                                                    models; consider abandoning the old 3500 controller and switchover to 9800 platform

  M.

[Joseph W. Doherty]

The only change I did was changing the DNS for end users...from ISP DNS to 1.1.1.1 and 8.8.8.8

Have you tried reverting that change?

[sagarshaha]

I haven't as I have 2 ISPs (4 DNS) so I was wondering if that's causing the issue as in this setup some of the samsung mobile users complained the internet getting disconnected and also our Sonos speakers sometimes wont connect.
Is it safe to give 6 DNS servers as below?
ip dhcp pool ***-asia_Wifi
network 192.168.124.0 255.255.252.0
default-router 192.168.127.253
domain-name ***-asia.com
dns-server 203.121.65.39 203.82.64.129 203.121.65.30 203.82.64.145 8.8.8.8 8.8.4.4 
lease 8

[Mark Elsen]

  - @sagarshaha                   Personally I think it's unreliable ; common practice is to restrict to two DNS
                                            servers which are actually working   => (checked before )

 M.

[sagarshaha]

Hi,
I did changed DNS and only kept two DNS. 203.121.65.39 203.82.64.129. Network worked well for last 2 days with less complaints but the new problem started is roaming. When people move around the desks, the wifi completely drops and disconnects. Does not even try to reconnect the wifi. We have to manually reconnect it. Any settings to check ? Appreciate your help. 

[Mark Elsen]

  - @sagarshaha                    1) Such issues such as suddenly during the last 2 weeks ; are suspicious and could
                                                   be related to resource exhaustion on the wireless controller : Reboot it

                                               2) Aireos platforms are getting old and outdated and should use last  release
                                                   available : : https://software.cisco.com/download/home/286312601/type/280926587/release/8.10.196.0

  M.

[sagarshaha]

Hi, 
Sorry to come back on this as the problem still exists. 
1. We have done the reboot still no luck 
2. Cannot upgrade as we are out of contract. 

Current situation,
1. The wifi just goes off completely and users have to manually connect back. 
2. For some users (including me) when I keep continuous ping to 8.8.8.8. After every around 30 successful pings, there will be "Request Time Out" for 4-5 times and then again ping successful. 
3. Any video or audio calls using Teams are never smooth. There will always be issues.The issues are same with call getting disconnected and with error "Hold On"

I really need help to review the config and suggest if anything is wrong. Happy to paste the required config if needed. Thank you so much for your help. 

[Mark Elsen]

  - @sagarshaha              >....2. Cannot upgrade as we are out of contract. 
                               Consider that  a fatal showstopper; as I said aireos is old and using the last release
                                     made available is mandatory.

  M.

[aleabrahao]

Honestly, it doesn't seem to be related to DNS, but perhaps it's related to RF, and the APs might be changing channels due to some kind of interference.

I don't know if you're using the 2.4 or 5 GHz band, but a test you can do (if you haven't already) is to test the device only on the 5 GHz band.

Another thing I suggest you check is the interval configured for the Channel Assignment Mode; the default is 10 minutes, but it's recommended to change it to a longer interval like 4 or 8 hours.

[Dustin Anderson]

I can't see DNS being the issue, unless the firewall doesn't let them out to resolve addresses.

Some things to check/try, but I haven't used airOS in about 2 years, so going off memory.

1) Fast transition. This is for roaming between APs

2) PMF or protected management frame. This is to combat spoof disconnects. This is possible for the issue, but would depend on if you have neighboring companies etc.

3) Client updates. I have seen apple updates have issues before, but it seems you are seeing it across multiple vendors so probably not the issue.

4) channel utilization. It's possible the channel is saturated where the devices can't talk and eventually disconnect. a cheap tool I've used in InSSIDer, but probably free scanners out there.

5) authentication/CoA. not sure how you auth clients or if it's just a PSK, but the RADIUS server could be sending CoA or deauths.

It can be hard to narrow down and enabling settings like fast transition and PMF will stop a client connecting if they don't support those features so test with caution. Most new clients should support as they are not new features.