Model : Archer D7

Hardware Version : v1 00000001

Firmware Version : 1.6.0 0.9.1 v002d.0 Build 160216 Rel.57110n

ISP : Telstra

Telstra NBN Optical Fibre to the Node VDSL
Telstra supplied sagecom Fast 5355
Using Archer D7 for swiching to provide more ports

The issue.
All other devices get internet when plugged into the WAN port of the Fast 5355 except the Archer D7. I would like to know why and how to make it work if possible.

Notes: The Archer D7 does get internet when plugged into a 10/100 LAN port on the Fast 5355 but we want to use the WAN port for its 1GbE speed. Would also be a bonus if we could use the WAN port of the Archer D7 as an additional LAN port. We are keen on re-using/recycling old hardware and don't want to waste the GbE capability of the Archer D7.

Extensive details:
Must use the Fast 5355 for voip as telstra wont release details.
Fast 5355 is also the only VDSL modem we have.

Gateway: Fast5355 Modem router
DSL: 1
WAN: 1x1000
LAN: 2x10/100
USB: 1
PTSN: 1
Phone: 1
Settings
IP: 10.0.0.138 255.255.255.0
DHCP: 10.0.0.1 – 10.0.0.254
---------------------------------------------------------------------------------------


Switch 1: TP-Link Archer D7 Gigabit ADSL2+ Modem Router
ADSL: 1
LAN/WAN: 1x1G
LAN: 3x1G
USB: 2
Settings:
Operation mode: DSL Modem Router Mode
Internet: br_8_35_0
Lan settings:
IP 1: 10.0.0.140 255.255.255.0
IP 2: 192.168.1.1 255.255.255.0
DHCP: Relay 10.0.0.138
-------------------------------------------------------------------------------------


Switch 2: Technicolor TG797v3
DSL: 1
WAN: 1
LAN: 3x10/100
LAN: 1x1000
USB: 1
PTSN: 1
Phone: 1
Settings: It just works without changing anything, isn't that nice?
------------------------------------------------------------------------------------


Trying to connect as such:
Telstra Fast 5355 (Have enabled WAN as LAN in settings)
LAN ---> Computers
WAN
|
V
LAN 1
Archer D7 LAN 2 ----> Office Computer
LAN 3
|
V
LAN 1
Technicolor TG797v3
LAN2-4
|
V
computers and servers.


Thank you for your attention to this matter.