Connection to other rooms lost when using line-in at Play5

Hello,

I am operating a Sonos S1 system with 10 speakers in 8 rooms. The music plays in party mode (i.e., all rooms connected). Everything works fine. I now added a turntable through the line-in of a Play5 (gen 1). Mostly, this works fine. However, often the sync between the rooms breaks down and the music only play on the two speakers and a bass booster that are connected to one pair in the room, in which the turntable is connected to one of the speaker. After a while, the other rooms pick up the music signal, but then loose it again.

I wonder whether it is too much bandwidth for the Play5 to simultaneously SEND a signal from the turntable to the system and to RECEIVE a signal from the system. Would the set-up be more stable if I were to purchase a Sonos Port and feed the turntable signal into the system with it (obviously, I would prefer not having to do that, as it involves extra cost)? Is there a way to stabilize my system so that playing music coming from a turntable in multi-room mode is better achieved?

Thanks!