@Jonny-Five-O Sonos is very very cumbersome against networks... they run on Multicasting Streams. I would suggest getting a Omada router that runs mDNS. If you get a ER605, buy the V2 (not the V1)....

@Jonny-Five-O Can you give us more details on your network? Router, switch, APs are you using?

@AurelioS Upgrade the firmware of your router to 1.4.0 and retest. https://community.tp-link.com/en/business/forum/topic/621532 Also update your Controller Appliance

@SusP Since this is happening on the Wireless and Wired, I would a few things: Upgrade to 2.1.5 and retest: https://community.tp-link.com/en/business/forum/topic/634790 Does the controller alert logs...

@ElvisV 2 things... we have to look at the signal strength of the client and look at the band its on. Goto the client list: click on the three dots on the right and check all columns. Check for...

@tim-hilt Click on the radio in the device list within the omada controller. goto config>advance> and its below.