Here you can see an AP on channel 40 that is slightly suffering, but in realist is working fine, what does the table below show for your one?
In terms of diagnostics there is a lot of infrastructure between your client and Google's DNS servers, so I would ping the local gateway for a better test of the AP and local switch / router only. If that shows loss and pinging it from a wired device does not then the wireless is where to investigate.
I have seen multiple instances where ping is not 100% reliable to the Google DNS servers, even with a wired connection and a fiber internet connection. I would suggest you also try to ping against the Cisco Umbrella servers at 184.108.40.206 and 220.127.116.11 and see how they respond. And if you really want to understand what is going on with an internet connection, a Cisco Thousand Eyes subscription will show the performance of every hop between your connection to the internet and any other device connected to the internet.