i am on maxis fiber broadband, i was given the TM branded HG8240H GPON, i can login to the web interface if i disconnected my fiber cable, if i connect the fiber cable, i can't access to 192.168.1.1 web interface at all. This makes me very difficult to change the VOIP setting because i can't check the connection status real time

i tried to do a hard reset of that GPON but it is still the same, anyone face the same issue and how to fix it?