If there's an issue with the NTD (Arris modem), it's more than likely an issue on the NBN network or a device fault.
I'd really suggest messaging us directly.
The team will go in and run a remote diagnostic on the Arris modem. Based on the test results, NBN will prompt us to either:
. Raise an appointment for a field technician to go out,
. Remotely restore the service from their side
. Determine whether the issue is Optus related