Try below method.

Off Sim 2 (prepaid) -> restart phone -> speedtest
Off Sim 1 (postpaid) -> restart phone -> speedtest

or

Put 1st sim (postpaid) to sim 1 card slot -> No sim card at sim 2 card slot -> speedtest
Put 2nd sim (prepaid) to sim 1 card slot -> No sim card at sim 2 card slot ->speedtest

This post has been edited by bingozero: Sep 14 2023, 06:17 PM