Voice not stable when using voice application , Skype , MS Team , Google meet - WLC

[Ethan and Mia]

Hi , My WLC is 5520  firmware on version 8.10.x   , All APs are .ac wave2  and  "FlexConnection Mode"   

I have an issue, When using the voice application such as Skype,MS Team etc. Sometimes voice not stable

-The internet source no any QoS

- client snr 20-25

What should I do for troubleshoot this issue ?

 - Wi-Fi QoS << I never did it.

 - capture client event while they using those application. <<  I never did it

Please suggest me , Thanks in advance.

[balaji.bandi]

how about when you connect to Ethernet is this work as expected?