Enable VLAN on WAN interface for Cisco SRP527W

Several years ago, I advised a friend of mine to buy the Cisco SRP527W, a SME DSL router with built-in voice capabilities. At the time, it was one of the supported devices for his broadband provider’s VOIP services.

Another motivation was the (uncommon at that time) ability to provide multiple WiFi SSIDs, so that he could maintain a “guest wifi” as well as his “trusted wifi”.

It took us several hours at the time, to setup the guest wifi (hint: add a VLAN, DHCP server config, then associate with an SSID), but since then it’s been working reliably, and the guest wifi has been a hit.

I recently helped the same friend move to a fibre broadband service. In New Zealand, if you want to terminate your fibre (PPPOE) connection on your own device, you need to configure it for a WAN sub-interface on VLAN 10.

Since it took us several hours (again!) to configure the SRP527W this way, I decided to record the process for anyone else struggling.

Step 0 : Reset the config (may not be required)

My friend’s SRP527W had been auto-provisioned by his previous DSL-VOIP provider, and certain administrative functions were disabled. We had to perform a system reset (default admin password is admin/admin, and user password is cisco/cisco) to restore functions. This may not be required under all circumstances.

Step 1 : Switch off DSL support to enable ethernet WAN

Before we could use the 4th Ethernet port as a WAN port, it was necessary to disable the DSL interface. This is done under Administration -> Switch Setting, and will reset and reboot the device.

Step 2 : Configure WAN interface

This stumped us for hours. You can’t configure a VLAN ID on the WAN interface. The dialogue box is there, but it’s greyed out. Eventually in frustration, I configured the WAN interface as an untagged, DHCP client interface, intending to connect it to the provider-supplied router.

After configuring a WAN interface, only then did it become possible to add a sub-interface, which permitted me to specify a VLAN ID.

So, happy ending. My friend has his SME router running dual-SSID, VLAN-isolated networks, happily connected to his new fibre provider.