network bandwidth insufficient to maintain playback buffer

Hi all,

So sorry for the repeat question but as I have another problem as well I thought it might be best to ask it separately.

Basically, I do get the bandwidth insufficient error but also when I don't get that if I connect more than 2 play:1 speakers to a sonos boost it again goes off. Basically 2 boosts are connected with wire to the sonos system and then each of the boosters are supposed to support 3 speakers on each floor separately. 

My diagnosis number is 799501210. 

Any suggestions are very much appreciated.