After a weekend of adventures trying to get a high performance 3rd party modem-router that works with iiNet FTTN I finally found one that works. Posting the configuration settings so other poor schmucks don't have to suffer the same frustration of finding a decent modem-router that works with this ISP and FTTN type NBN.

This is a great modem-router, excellent performance, and one of the very rare 3rd party options that is compatible with iiNet FTTN
 

Why was this so hard?

Wondering why it is so hard to find a compatible 3rd party high performance modem-router for this ISP (iiNet)?

1. Firstly, you need one that meets the iiNet compatibility specs (search their help site for "nbn-byo-modem-hardware-compatibility") 
2. Then, you need to cross reference modem-routers that meet those specs with the list lower down that page which lists all the models with known incompatibilities (spoiler: this pretty much rules out most of the modem-routers on the market!)
3. Finally, you need to find a retailer with the device you've chosen in stock. Because by this point you're down to just a few options, this is actually really hard!
4. The configuration settings (above) to set up the device for iiNet are not listed anywhere official, hence this post :-) 

A final point of interest

When NBN rolled out they made a rather short-sighted decision to do  Fiber to the Node (FTTN) and Fiber to the Buiding (FTTB). These types of connection requires that you have both a modem, and a router (or an all-in-one modem/router as described above). Other (better) types of connection (FTTP/H, FTTC, HFC) do not require a modem; you'd plug straight into the ethernet in the wall, or add just a router to add wi-fi capabilities. Because these later types of connection are much more prevelent elsewhere in the world, the manufacturers are investing a lot less in modems and modem-routers, and a lot more in wifi routers.  So for iiNet FTTN/B customers, you have the double problem of very specific needs from the ISP, AND the limitations in availability of modem-routers overall.  Le sigh. 

I hope this post helps someone!