Welcome to TPG Community!
We have located the account using your community details and we can see that you have been in touch with one of our technical specialists.
We have checked the status of your service and we are not detecting any fault on the line or network at the moment, but we can see that there's no router connected as you've confirmed that the NBN Box is located in the basement.
For this type of set up, you can normally connect the router to an available ethernet socket inside the premises.
As you've mentioned, there's no cable connecting from the NBN Box to the ethernet socket, thus you will need to coordinate with your building admin to check the internal wiring.
Should you have further queries, feel free to drop us a message. Thank you.