Netgear M2 unstable Internet Connection

I used to own an M1 mobile router, I was very happy with. When that one died I went for the newer M2 and problems started. Sonos speakers (wired & wifi) started intermttently dropping out (losing connection to streaming services, especially Apple Music) also streaming apps on mobile devices (iphone/ipad) started to show SSL errors (intermittent connection failures) when playing (especially Apple Music). This never happened with the M1. Other internet services (youtube, browsing, gaming) are fine … Any advice?