Would you please post the type of NBN connection you have please? FTTP, FTTN, FTTC, HFC
If you are unsure please go to
enter you address and click check residential.
The type of connection helps for troubleshooting.
Was the Sagemcom dropping out?
Make sure the Taipan is using the latest firmware , I can't find and Optus specific info but a TPG user needed version 1.00.19 or later before their Taipan connected properly.
IF that does not fix it, you might want to try and compare the "Connection Type", "VDSL2 specific settings", and "VLAN ID" sections of the official Optus DSL setting with the DSL setting in the Taipan.