Welcome to the community!
A Dynamic IP address may change whenever your connection restarts; technically every 24 hours or multiple times in a day.
Unfortunately TPG do not have control or access with the new IP Address after the changes.
You have an option to get a Static IP however we only offer that with our NBN Business plan.
You may check this link for more info: NBN BUSINESS PLANS
Feel free to let me know should you have further queries.