If you’re having difficulty discovering your Sonos devices, my thoughts here are that anyone with the type of issue ‘perhaps’ could have a multicast ‘device discovery’ issue across their network that’s preventing the controller device from communicating with their Sonos speakers. See attached re: SSDP/mDNS.

Such communication failure can occur across networks that use WiFi extenders, EoP adapters, or if managed switches are misconfigured. It can also happen if some settings on a local router are incorrect, or there’s software running on the mobile device that is getting in the way of the multicast communication, such as security software, VPN client, firewall, site blockers etc.

I’d perhaps investigate further in the areas mentioned and if still no luck, then it maybe best to reproduce the issue(s) seen and then immediately submit a Sonos system diagnostic report from within the Sonos App, note it’s reference and contact/chat with Sonos Support Staff via this LINK and see what the Staff can perhaps suggest to help you to resolve the matter.