Orbi firmware v2.5.1.16 Satellites and Sonos

Interestingly we had something similar with our more remote Sonos speakers (we have the Sonos Soundbar connected via Ethernet and then all other Sonos speakers connect using SonosNet which is their own mesh network). Also note that the newer Sonos Move is an exception here as it connects to your WiFi network and not SonosNet.  If you don't have any Sonos products on Ethernet then your issue might be different to ours.

I discovered that SonosNet was using a channel very close to the Orbi 2.4Ghz network so I changed the channel for SonosNet (using the Sonos app) and we've not had an issue since.  You can also set Orbi to use a fixed channel for the 2.4Ghz network if you prefer to move that away from SonosNet.

I had put it down to a number of neighbours recently upgrading to the fibre (FttP) provider so the number of overlapping WiFi networks had also increased. Important to remember that external factors can influence WiFi even though you know you haven't change anything.

EDIT: Also just to add that if you look on the Orbi app you'll see that all Sonos speakers show as wired and not wireless (Sonos Move is the exception as I said) if you have one Sonos speaker connected to Ethernet even though all other speakers are "wireless" but using SonosNet (Orbi sees those speakers as going through the wired speaker).