I recently switched to Optus pre-paid and have found that my mobile data speeds on my new Samsung Galaxy J2 Pro are ridiculously slow from my home address at Casino NSW 2470. But it speeds up at around 2AM in the morning. BTW it has taken about 30 minutes to load the Optus help forums just to post this.
Things that I have done:
Hi - sorry to see you struggle at those extremely low speeds. Is your signal strength indicator showing maximum bars and are your speeds better when you are in town and nearer to the Optus Cell Tower located at the corner of Walker and Hare Streets? Factors such as limited cell tower capacity, user demand during peak times, distance from the tower, signal strength of various frequencies used by Optus, position in home and topography all influence connection speeds. Optus may also be doing maintenance work or upgrades that could be impacting on the service.
Do you have any friends who are also on Optus so that they do comparative tests at your home to see if their phone performs better? Either in home or at Optus shop, another test could be to put your new Optus SIM into an unlocked mobile phone to see if any noticeable change in speed occurs.