Set persistent CARP maintenance mode on the primary.
Status > CARP.
If you ALWAYS want the primary to boot into maintenance mode there is no supported way to do this, but you can install the shellcmd package and sort of force it.
You could install the Shell Command package (Will be in Services > Shellcmd after installation) and try to run this as a shellcmd.
/usr/local/sbin/pfSsh.php playback enablecarpmaint
Note that this will not discriminate as to the reason for the restart. Every time the system boots, it will set CARP Maintenance Mode.
You can fail back using the Leave Persistent CARP Maintenance Mode button in Status > CARP.
This is not really supported but might be a reasonable workaround for the issue you are describing.
Please let us know if this has the desired effect. I tested on 2.4.4-p2.
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