If you have MikroTik LtAP with two SIM cards you can make simple scheduled task that changes currently active card with other:

Script looks like this:

:global simSlot ([/system routerboard modem print as-value]);
:if ($simSlot=”sim-slot=down”) do={:system routerboard modem set sim-slot=up; :log error message=”SIM UP active!”} else={:system routerboard modem set sim-slot=down; :log warning message=”SIM DOWN active!”}

Example (for testing purposes I have reduced time to 3 minutes but it works also with 24 hours …):