There are lots of things you can perhaps consider here. Here are a few things to initially try..

• If using WiFi, then try a different fixed non-overlapping WiFi channel, using either channel 1, 6 or 11 and set the channel-width to 20Mhz only.
• If using SonosNet, then aswell as the suggestion above, set the SonosNet channel in the Sonos App network settings to a different channel to the one chosen for the router WiFi and set the wired device at least one metre away from any wireless access point.
• Try unpairing and swapping the left/right speakers over, so they swap L/R audio channels.
• Move speakers away from things that may cause interference, baby monitors, dect Home phones, microwaves, or other WiFi/Bluetooth devices.
• If relevant, turn off crossfade/shuffle to help reduce the load on the players memory and remove any old Music services no longer in use.
• If a device is wired, try using a different Ethernet cable, or try using WiFi instead.