Hi Anson, This is a public forum filled with fellow customers.
You need to contact Optus directly to diagnose your issue.
FWIW any business that relies on the internet should have a backup plan in place as no matter who the provider is there will be down time. I'd look into a phone plan with good data (maybe prepaid long expiry date?) that you can use as a hotspot etc. Or possibly chat with the store next door. If you are with different providers you could set up an emergency cable that you could plug into each others router in the event the internet goes down for more than say 30 minutes?