Ability to add a VLAN tag on the default network on Max routers

As the default untagged network cannot be disabled it would be ideal if it was possible to add a VLAN tag to this default network on the routers, we have instances where clients run multiple networks to site and all have VLAN tagging setup so no untagged networks at all.

This would be most useful on the Max series routers but possibly on Balance devices as well.