Seems more like an issue with your network, rather than the Sonos. I’ve had Sonos for more than 10 years, and with some care and dedication to keeping my network signal clean, I’ve not experienced any issue.
With no information about your particulars, there’s some generic suggestions. First, read the wifi interference FAQ and apply as many of the potentials there as may apply. In my home, with around 18 or so devices, I’ve found a ‘wired’ setup to work the best. All that required is a single Sonos device to we directly connected to my router with an Ethernet cable. In my case, I started with a BRIDGE, but upgraded to a BOOST when I saw reports of the common failure point of the BRIDGE’s power supply. I was also enticed by the BOOST’s newer WiFi signal, increased interference rejection, and SonosNet 2.0.
At an early point, I had similar issues with rooms disappearing from my system, that turned out to be an issue with my router handing out duplicate IP addresses when my Sonos rebooted after an update. Easily rectified by figuring out how to assign reserved IP addresses in my router. Still don’t know why the router failed in that manner, but I do take more care now to keep the router’s software up to date, and reboot it every other month in case there’s any issue.
The network in your home isn’t static, unfortunately. It would be great if we could just set it once and walk away. Unfortunately, with neighbor’s new networks, devices not being kept up to date, there’s always the potential for ‘change’ completely out of your control.
In the meantime, if none of the advice I’ve written here is of any help, perhaps you could provide a bit more information about your specific setup, when you contact Sonos Support directly to discuss it. They’re extremely helpful in figuring out what can be done to assist in individual situations.
I usually suggest the phone folks, they have more tools available because they're on the phone with you, but they are available Monday through Friday during business hours. The Twitter support folks are available 24/7.