VLAN with an id of 0 isn't possible on the new interface last I checked. Which, granted is a weird thing to do, but...
There are off-the-shelf all-in-one Asus home routers that do VLANs?
yes, thos is quite rare thong. Could you describe the reason behind it?
That's not a valid vlan ID for most vendors (Reserved) and can also be a security vulnerability, as it can allow traffic to elevate its Class of Service and hop vlans via this method.