Their older stuff did not really supported it as well..
you could do it, but just because the USG software was a fork of Vyatta that had a way for doing it and Ubiquiti never put the effort to block it..
So while there was a way of doing it, it was never really officially supported..
But this is why when it came time to upgrade my USG3 i choose to migrate to Opnsense (pfsense fork) instead of upgrading to the latest Ubiquiti router.
you could do it, but just because the USG software was a fork of Vyatta that had a way for doing it and Ubiquiti never put the effort to block it..
So while there was a way of doing it, it was never really officially supported..
But this is why when it came time to upgrade my USG3 i choose to migrate to Opnsense (pfsense fork) instead of upgrading to the latest Ubiquiti router.