Are you on FTTP? If so, what lights are on on your NBN box? If Optical is green, the problem is almost certainly at your end (possibly router). BTW, IF you are on FTTP, the modem function is now in the NBN box; your own device is a router.
NBN box optical is all lit up green. The router supplied by TPG is connected correctly is all lit up with blue for wifi, security plugged into LAN It all just stopped last night. We’ve only been operating for 4 days the router is brand new