Ok some tricks for setting up ##5GOptusInternet from my point of view
It was disappointing that my Optus rep could not give me any more info to help my WIFI or some ethernet issues. Seems like they are in a big learning phase as well and could only suggest I try Google Mesh or Nokia Beacons (which I cannot find anywhere in AUS). If you need to set up a mesh... here is an interesting link... https://www.ozbargain.com.au/node/557643?page=1#comment
In short, it you cannot physically see a cell tower from your house or appt, don't bother with 5G Internet... you may find that you cannot get a good connection...
I hope this helps others who are trialling the service.
I am still in my free month, so will keep testing over the next two weeks before I switch off my NBN.