After 3 hours of setup for a novice, and searching the internet far and wide to finally get my connection going I thought I'd share the goodness.
GL MT6000 Router connecting to a DLink 245GE / AC1200 modem over RJ12 VDSL (NBN)
DLink 245GE modem setup
WLAN VDSL connection, bridging mode
WLAN Port bind(!!!!) the VDSL bridging connection to Lan Port 2
LAN DHCP off
Optional but I also changed the static IP of the modem to 192.168.8.* to match the MT6000 default range, as after DHCP is switched off you'll lose sight of it
MT6000 router
WLAN DHCP auto
Cable from WLAN (Port 1 default) to Port 2 on modem
May need to contact your ISP to kick your connection, or will come good eventually. Aussie broadband have a kick option in their portal.
Then follow the instructions below keeping your IP as default 192.168.1.1
Connection Type: Bridge Mode
Select Bridge Mode to use the DSL-245GE as a network bridge to extend an
existing network.
IPv4 Settings
Connection: Select Bridge Mode.
Protocol Select IPv4, IPv6 or IPv4/IPv6 for both IPv4 and IPv6 addressing
mechanism.
Connection Type: Select Bridged Only LLC or Bridged Only VC-Mux as the
encapsulation method. This is only available for ADSL.
Click Save when you are done. Or click Delete to delete the configuration
profile for the interface.
Then connect from a LAN port on the 245GE to the WAN port of the MT6000.
Set Ethernet on your MT6000 and use PPPoE and enter login details or appropriate protocol for your connection (may need a VLAN ID depending on your ISP). Hopefully can copy these settings from your 245GE before you reset while it's working as a modem/router.)