Anyone successfully got an ASUS DSL-AC68U working on a Spark (Telecom Xtra) Fibre connection?

Background:

• The provided device is a Huawei HG659b, which has some good modern features and tech specs, but under the demands of heavy users - it can't cope, and maxes out its tiny little processor, resulting in extreme reduction of traffic throughput (until you power-cycle the device). The ASUS on the other hand is a very expensive device with slightly improved tech specs and functions, and seems to handle heavy lifting with ease.

ASUS says my device supports Fibre:

• asus.com/Networking/DSLAC68U/overview/

   

  • "Compatible with ADSL2/2+, ADSL, VDSL2, fiber and cable services".

Re-purposing a LAN port:

• The idea is that you provision one of the LAN ports as your WAN port
• This LAN (WAN) port connects directly to the ONT (optical network terminal)

VLAN tagging:

• According to online posts, its simply a matter of tagging the traffic with VLAN ID 10. 
• As far as I can see, a long time ago you had to set the VLAN ID via "LAN > IPTV", but have since released better support VLAN tagging WAN traffic to better support ISP's that have that setup.
• Apparently this works easily with the Router/Non-DSL version of this model (RT-AC68U), due to the native support of WAN VLAN tagging.

Google-Foo:

• I have reviewed many posts on the subject, but over the years, no new reliable source of information has come to light.
• I have tested with 3 different versions of the firmware, included the latest (v3.0.0.4.380_7712).
• I've setup my device as per these easy to follow screenshot instructions, which I found here: pbtech.co.nz/ASUSISPSettings#SparkAC68U (tested using 2 firmware versions which are newer than the one in the post, and one firmware which is older than the one shown in those screenshots).

Any users out there got this to work successfully?

Any Spark techs know how to get this to work?

-Az