S21 that I used with Verizon then T-Mobile. Volume key all the way down is vibrate, one more press and was on mute. Switched to AT&T few days ago and it will no longer go down to mute. Stops at vibrate. Can only assume that the SIM card install packet changed something but neither AT&T support, Samsung support nor 2 days worth of google gave me a fix. How do I get my mute option back via the Volume Down key?