Assuming you’re running the devices on your routers WiFi signal at the moment, perhaps set its 2.4Ghz wireless band to either ‘fixed’ channel 1, 6, or 11 as they provide a non-overlapping signal. Then, if the router allows, set the channel-width to 20Mhz only and see if that improves things for you. See this support link:
https://support.sonos.com/s/article/4769
If you have left a single Sonos device wired to use a SonosNet connection, then do these few things (this is in addition to the router changes suggested above)…
- Ensure the wired device is direct to the router, if practicable, or a wired switch that links direct to the router. (Do not use a HT surround, or Sub, as the wired device).
- Keep the wired Sonos device at least one metre away from your router, or any other wireless device.
- Set the SonosNet channel at least 5 channels away from your chosen router channel. https://support.sonos.com/s/article/1219
- If you do not have any Sonos portable devices (Roam/Move) then remove your WiFi credentials from the Sonos App. See this link: https://support.sonos.com/s/article/3488
- Optionally, consider reserving your Sonos IP addresses in your routers DHCP Reservation Table to keep them fixed to the same address on the network.