My ISP delivers voice and data on two VLANS - VLAN100 (data) and VLAN660 (voice). From ER605 configuration, I can terminate VLAN100 with PPPoE for the data connection. However, I need to switch VLAN660 from the WAN port into my LAN port, so that my IP PBX (on VLAN660 on LAN network), can talk to the service provider voice server. So far, I have been using OpenWRT software, which allowed this configuration easily.
Currently, the ER605 prevents me from configuring more than one VLAN on the WAN port. And I cannot find any configuration to map the same VLAN on WAN and LAN ports (the configuration prevents it).
Can you please let me know how to configure my network?
I'm inserting my network topology diagram below.