After changing Cisco 5520 to 9800, latency increased.

[SPKV]

Hi,

Has anyone experienced increased latency after replacing AP and WLC from 2702I/5520 to 9164I/9800-40?

AP2702I + WLC5508 in centralized (AP local mode) and C9164I + C9800-40 in centralized (AP local mode)

Same config, same environment, same radio (5GHz and tested on the same channel before and after),

or that the 9800 has more work or features, resulting in more latency than the existing (AP2700/WLC5520)

[marce1000]

   - I would not consider  a ping and or ping tests  only, being  a determining factor to conclude on wireless performance (including latency)  ,  you may consider more elaborate tests such as https://iperf.fr/ to determine wireless performance.
(Appendix) : Review the C9800-40 configuration with the CLI command show tech wireless , feed the output into :
                           https://cway.cisco.com/wireless-config-analyzer/

 M.

[JPavonM]

As @marce1000 is saying, using remote connectivity to perform tests is not best practice.

Try deploying a local iperf server to test with.

Regarding your question, end-user devices operating with new standards, as far as they all do support ithem, and no other devices are on the RF neighbourhood that could be increasing contention, should perform better. If traffic is locally forwaded from AP to LAN then the pereformace should be equal or better, if it's centrally forwarded (anchored or AP in local mode in Cisco wording) then look at the whole path.

Signal quality (SNR that mandates the MCS index the station is using), channel contention and channel load, should be considered as part of the tests, and add to the equation the LAN/MAN/WAN load and bandwidth, and the remote service load, and delays in the path if it's hosted on the Internet then different traffic paths chaning all the time maybe impacting final results.

[Rich R]

Also depends what you were using for the test.  If you were using a PC with an out of date WiFi network driver which worked fine with 802.11ac but had bugs affecting 802.11ax then that could explain what you're seeing so make sure the OS and driver are up to date.

You don't mention what version of WLC software you were using but make sure it's up to date as per TAC recommended link below.