Having the same issue. It's maxis routing. My friends on unifi do not have this issue. You need to run ping test and trace route during the issue and open a ticket to maxis.

Try this website

https://deepfocus.io/overwatch_ping.php

You will need to compile the ping and tracert result during the issue and when it's working properly.

Then when you call maxis customer service they will require evidence for them to take you seriously. These logs will be sufficient. If they can't solve the problem you have the right as a consumer to terminate the contract and sub unifi.

This issue been around for many years now but maxis do not care coz not so many ppl complain and follow up on the issue.