downgrading rb frameware from new version 6.40.5 to older version like 6.37 cause generating unknown port in bridge !! where that unknown port came from ? and when remove it then reboot the router it generated again !!! how to remove it permanently ?
I think you missed the technology train. One is generally not supposed to go back to lesser capable or lesser safe software…
Why dont you start from defaults…
It may be safest to “upgrade” to the latest bugfix variant. They are normally rock solid and rarely have issues.