Do not consider VLAN capable only interfaces that have VLANMTU flag. This flag is used to determine if that interface can do 1500 MTU even with VLANG tag set.
Related issues
Bug #9548: Do not use VLANMTU flag to decide if interface supports to run VLAN
Fix #9548: Do not rely on VLANMTU flag
Do not consider VLAN capable only interfaces that have VLANMTU flag.
This flag is used to determine if that interface can do 1500 MTU even
with VLANG tag set.