Hasn't your part of the world been getting some pretty extreme weather lately? That could be a contributing factor (i'm not 100% sure about this one)
What sort of internet service do you have? For example, ADSL, Cable, NBN etc.
If you have ADSL it may be worth doing an isolation test. Check out this link for instructions: https://crowdsupport.telstra.com.au/t5/General-Internet-KB/How-to-perform-an-Isolation-Test/ta-p/55014
Once you have done an isolation test, monitor your internet for an hour or so and see if the issue is still there or not. If it is, then it might be time to call Telstra. However, if the issue is resolved while isolated, that indicates an issue with your splitter or home phone.
What sort of internet service do you have? For example, ADSL, Cable, NBN etc.
If you have ADSL it may be worth doing an isolation test. Check out this link for instructions: https://crowdsupport.telstra.com.au/t5/General-Internet-KB/How-to-perform-an-Isolation-Test/ta-p/55014
Once you have done an isolation test, monitor your internet for an hour or so and see if the issue is still there or not. If it is, then it might be time to call Telstra. However, if the issue is resolved while isolated, that indicates an issue with your splitter or home phone.