Past few days, my NBN box is getting bad signals, Coneection Light is flashing blue and red, DSL light is flashing, LAN light is off. The modem then ran on Mobile backup mode, now the NBN box light is all solid blue except LAN light, my Modem doesn't seem to get connection from NBN box, the cables is all don correct because it was working for months, I even changed the cable too.
So now my modem still running on Mobile bake up, NBN box still solid blue except 4th LAN light is off.
If you have a PC or Mac with an Ethernet port try connecting the PC or MAC directly to NTD and check if the the lLAN light on NBN NTD turns on and the PC or MAC has internet access. If you have internet access then Telstra modem is faulty and you could try a factory reset of the Telstra modem.. If you don't have internet access then NBN NTD is faulty. The only thing you can do to fix either fault is to contact Telstra support.