You cannot add a port to a VLAN:

If you attempt to add a port to a VLAN and get an error message similar to:
localhost:7 # configure vlan marketing add ports 1:1,1:2
Error: Protocol conflict when adding untagged port 1:1. Either add this port as tagged or assign another protocol to this VLAN.

You already have a VLAN using untagged traffic on a port. Only one VLAN using untagged traffic can be configured on a single physical port.

You verify the VLAN configuration using the following command:

show vlan {virtual-router vr-name}

The solution for this error using this example is to remove ports 1 and 2 from the VLAN currently using untagged traffic on those ports.

If this were the “default” VLAN, the command would be:
localhost:23 # configure vlan default delete ports 1:1,1:2
You can now re-enter the previous command without error:
localhost:26 # configure vlan marketing add ports 1:1,1:2

VLAN names:

There are restrictions on VLAN names. They cannot contain whitespaces and cannot start with a numeric value.

VLANs, IP addresses, and default routes:

The system can have an IP address for each configured VLAN. You must configure an IP address associated with a VLAN if you intend to manage (Telnet, SNMP, ping) through that VLAN or route IP traffic.

You can also configure multiple default routes for the system. The system first tries the default route with the lowest cost metric.