Today i have had a problem with 3 external internet connection. What i did at the very beginning of configuring it was that I haven’t choose which interface is the PRIMARY and which is BACKUP.
At the very beginning i have only one external wan so there where no problems but, after some time i have had second and about 3 month ago third external wan.
When one interface was down whole traffic did not know which other interface he had to choose 😉
Today i have set it up properly and voila everything works as planned.