Welcome to the community!
We recommend the best thing to do first is check if there's an outage on the NBN network.
We have created this article that can guide you on How to Check for NBN Network Outage
If there are no known outages in your area you may perform basic troubleshooting, we did an article that you may find helpful see this link below.
In this case, Flashing red light on NBN-NCD means a fault line causing the service not to work. We've seen that you have been in contact with one of our Technicians and this issue has been raised to our Engineering Team and now under investigation.
An NBN Technician is scheduled to check your service, appointment details will be provided when it becomes available via SMS or Phone call.
Let us know should you require further assistance.