Sonos play 1 constantly disappearing from system

Hi please help. Nothing has changed since November when I switched to BT smart hub 2 with new WiFi disc. Everything was working fine until the last few weeks then the 2 play 1 devices I have started disappearing from the system all the time. I have gone through all the resetting solutions changed WiFi channels to both 1 & 6 ( after switching off smart WiFi). The result is always the same. It works for a few minutes then looses connect and I have to search for the system again and go through the same reboot and checking procedures only to end up with exactly the same result.