Grouped AirPlay speakers play out of sync
If you are playing music from an AirPlay device to a group of AirPlay speakers and a delay is heard between the speakers, try the following:
If playing from a group of AirPlay speakers, check if there is a mix or AirPlay 1 and AirPlay 2 speakers in the group.
If you have some speakers that support AirPlay 1 and some that support AirPlay 2, you can play them together as an AirPlay group by streaming via AirPlay 1 rather than AirPlay 2. When playing older and newer system together this way, audio among the systems might be out of sync. For multi-room sound that plays in-sync, group only AirPlay 2-compatible products.
Reset your product.
Much like rebooting a smartphone, your product might need to be reset on occasion to correct minor issues. For more info, see Resetting your product
Reboot your router.
Routers may need to be reset from time to time—much like rebooting a computer. Disconnect power from the router for 30 seconds, then wait for it to start up and connect. (Note: Any device connected to the Internet will be interrupted during the reset.)
If grouping mulitple Bose systems, check if a Wi-Fi network extender or repeater is in use.
Bose systems that you want to play in sync as a group might play out of sync if some systems in the group are connected to a wireless range extender and others are connected to your router. Since the extender receives and then re-broadcasts signal from the router, systems connected to the extender could receive signal later than those receiving signal directly from the router. To avoid this for systems beyond the range of the router, connect them directly to the router with an Ethernet cable (if possible). Otherwise, try repositioning the systems or router so they all connect either to the router or to the extender.