When QinQ is enabled on the switch all S-VLAN member ports must be categorized as either port-type customer-network or provider-network (See Customer or provider ports in the provider network).
All ports of a QinQ-enabled device default to provider-network. Any ports participating in the provider bridge used to connect to customer equipment must be manually configured as port-type customer-network. In a mixed mode device, ports that are members of C-VLANs and that do not participate in the provider-bridge cannot be configured to any port-type.
The following command allows you to configure the appropriate port-type.