I live in a suburban Melbourne area about 10 km from the city. I previously used an Amaysim without any issues. I now have a Boost sim. I can use it for data purposes anywhere. I can also make and receive phone calls anywhere other than in my home and for an area up to 50 metres outside my home.
There is no outage in my area.
Today, the 4g symbol disappeared as I approached the front gate. at other times the 4G symbol is not present until I turn into the next street - maybe 50 metres distance.
I receive a missed call message when anyone tries to ring me.
My partner still has an Amaysim and it works without issue.
Ironically I purchased Boost as I wanted coverage for non metropolitan areas that are poorly covered by the Optus network.
I would suggest lodging it with Telstra's team as a coverage problem so they can have it looked at.
Telstra just mustn’t have coverage as good as Optus does at your house. No real solution except to go back to an Optus provider. You could look at https://boost.com.au/coverage-map/ and see what it says.