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I was able to check our records and from what I gathered, our Engineering Team is already monitoring this case. An Engineer spoke to the Account Holder's son yesterday and he was advised to check the status of the NBN NCD when the connection drops out to determine if this is an issue with NBN's network or with the modem. Let me know if you can supply us the information so we can relay it to the Case Engineer.
It appears that your connection may have stabilized at this point. Your modem has been connected for 19 hours without interruption. Nonetheless, our Engineering Team is still monitoring the case and will reach out to you via SMS or phone call.