I changed my plans to NBN Cable Broadband SL Bundle 100 last year, but recently there have been issues. My internet speed is around 70-80 mbps at normal speed, but over the past week my internet has lost speed, around 1-5 mbps for a while (like lost connection). Then it resumes normal speed, then loses speed again, and it repeats. I restarted my router and nbn box, but the problem still exists.
We've created an article that might help you resolve your connection speed issue.
If you are using a WiFi connection, then signal interference might be causing it. Here are some articles that might help improve your home WiFi network.
If the issue persists, please send me a PM with your TPG username or customer ID number so we can assist you better.