UniFi DD-WRT Vlan Tagging Setup Example

Generally the steps are:

1. Create a VlanX with 500 tag number based on the WAN Port "VlanX" assignment
2. Save, then Apply Setting, reboot the router
3. Assigned the created VlanX.500 to the WAN Port Assignment
4. Note: If cannot find the created VlanX.500, then either the device unable to support or the physical port is different.  Either way it's going to be complicated, better get a device which can support 3 digits vlan tagging.
5. Unbridged both VlanX & VlanX.500
6. Save, then Apply the setting, reboot the router again

Make sure the rest of setup including PPPoE user ID & password is correctly entered before connecting the WAN to TM's BTU unit.

Buffalo WHR-G300N V1
Ralink RT3052F @384Mhz  (Same chipset as TM's DIR-615 Gx)

TP-Link TL-WR941ND V3.2
Atheros AR9132 @400Mhz with AR9103 WiFi NIC

TP-Link TL-WR741ND Ver1.8
Atheros AR7240 @350Mhz with AR9285 WiFi NIC

.