At the end of this page there are the older FW: https://en.shanling.com/download/56

Hey guys, just discovered something weird, after upgrading to 3.6 the Bluetooth connection became very unstable and connection dropped already when being 1m away from the M0, downgrading to 3.1 fixed it for me. Tested with Soundpeats Air 3 with different BT profiles: LDAP, aptx, SBC, AAC occurs...

Some users have reported SQ has become worse and some hiss when connected to BT gear in stand by mode (no music playing)

Good point, I am interested as well if sound issues have been improved?