This is indication of either wifi interference or duplicate IP addresses…something is getting in the way of your controller when it’s sending commands to the computer that runs the system on your speakers. 

Of course, because the speakers are temporarily losing connection to your router for some reason, TuneIn, when the speakers reconnect, considers the stream to be a ‘new’ one, and sends its normal pre-roll advertisement. If you address why your speakers are losing connection, that issue will stop as well. 
Sonos doesn’t make a WiFi switch, so I’m completely befuddled by that statement. 

Have you tried to call Sonos Support directly to discuss it?

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 network and Sonos system. And should be able to help pin down why your speakers are dropping off your network. 

Raw network speed capability is not the whole story. WiFi interference and network configuration issues can impede SONOS performance.

As an analogy, I was once slowly struggling along in my old clunker during glare ice conditions when a fancy 4-wheel drive sports car blasted by in the passing lane. The driver was probably snickering at my  slow, old car. A few miles later I slowly passed that sports car because it had blasted a few hundred feet off the road into a field.