Welcome to the Community!
If the Optical light is red, there's a problem with either the NTD box or the fiber line itself. We need to conduct a test to check if there's something that can be done from your end to have it rectified or if this needs to be escalated to NBNCo directly.
However, in order for us to the test, we need to pull up your account. Unfortunately, we can't seem to find your TPG records using your community details. Can you PM us your customer ID or username together with your service address?
For your reference: How do I private message (PM) in the community
Thanks for providing your account details via PM.
I have already performed the tests and based on the results, this issue needs assistance by NBNCo. From what I can tell, they need to check the fiber line going to the NTD box.
I have already escalated the case to our Engineering Team for assistance. Updates will be provided to you directly via SMS or phone call on the number we have on file by a Case Engineer.
Should you have other concerns, don't hesitate to drop us a note.