I understand that there is no more "cable modem" internet service?
Is this Cisco Gateway model DPC3925 still of any use in Singapore? Or are they not usable for anything at all already.
The router you mentioned is no longer functional for Fibre Broadband services. You can refer to https://www.starhub.com/personal/support/device-trouble-shooting/broadband/equipment-guides.html for the updated routers requried.
For further advice, you may wish to consult the router manufacturer instead.