No internet

Level 2
We're doing a first time connection with modem delivered last week from TPG.

The FTTC NBN box is OK with four blue lights, the wifi is good, but the internet light on the modem is NOT ON and internet status is ‘disconnected’. Have switched things off/on a couple of times and left it for a while, but still no internet connection.

Have been trying to get through on the TPG technical support chat for four days, with no luck.

How can we resolve this?