i have 3 unit EAP660HD and 1 unit EAP245 in the office
and the problem is our ping is not stable will suddenly time out frequency perday will happen many time per hour . 4ap have the same issues . the wifi is connected but ping will frequency time out 3-10 second  . the voip call not stable , end user laptop wifi connection also not stable .  the meeting zoom , team call also discounted frequency . the AP just install up on out head celling . and all user is getting full bar wifi its not distance issues .
and the channel 2.4 have setup difference channel
1floor eap600HD channel 1  txpower Low ,
2ndfloor eap660HD channel13 txpower High and EAP245 channel6 txpower High,
3nd floor  channel1 txpower Low  .

as monitor when the ping time out the channel utilization is 17% , all the AP is Stand-alone mode not mesh 
please help us up. if you need more information i may provide you with the setting and log or ect . we have install the controller to manage . 



Reply from 192.168.1.1: bytes=32 time=2ms TTL=64
Reply from 192.168.1.1: bytes=32 time=1ms TTL=64
Reply from 192.168.1.1: bytes=32 time=2ms TTL=64
Request timed out.
Request timed out.
Request timed out.
Request timed out.
Request timed out.
Request timed out.
Reply from 192.168.1.1: bytes=32 time=3ms TTL=64
Reply from 192.168.1.1: bytes=32 time=4ms TTL=64
Reply from 192.168.1.1: bytes=32 time=4ms TTL=64
Reply from 192.168.1.1: bytes=32 time=3ms TTL=64
Reply from 192.168.1.1: bytes=32 time=3ms TTL=64
Request timed out.
Request timed out.
Request timed out.