Not sure how you came to the conclusion that your Wi-Fi is fine, but it’s pretty clear evidence of the Sonos speaker (the PLAY:5 on Sonos 1) having difficulty maintaining a connection to the stream of data, but instead failing, then reconnecting.
My guess would be a simple duplicate IP address issue, since it’s only affecting one speaker, but it might also be wifi interference . For the duplicate IP issue, unplug the PLAY:5 from power, and then reboot your router. Once the router comes back up, go ahead and plug back in the PLAY:5. It will request a fresh IP address from the refreshed router.
Of course, you could always submit a system diagnostic within 10 minutes of experiencing this problem, and call Sonos Support to discuss it.
There may be information included in the diagnostic that will help Sonos pinpoint the issue and help you find a solution.
When you speak directly to the phone folks, they have tools at their disposal that will allow them to give you advice specific to your Sonos system and network.
