My system compromises of a gen 1 beam in my sons games room, A gen 1 beam 2 play ones and a sub in the living room and finally 2 play ones in the kitchen.
The 2 play ones in the kitchen have so much lag on play, stop volume up and down etc… the other speakers are fine. Now here comes the head scracher the 2 play ones are in the same room as my Unifi AP and connected to the AP on 5ghz and have a strong signal the other rooms are further away and have dropped to 2.4ghz but they all do not have any lag at all.