Telstra Cable Connectivity Issue

[wasteland]

Hi

I'm really confused right now.  I have a telstra smart modem which comes with a telstra cable adapter.  My PC is connected directly to the modem via a cable.  It was working fine forever but this morning my PC lost access to the internet.  The cable adapter now shows a green flashing light for "downstream", no light for "upstream" or "internet" and the "network" light remains blue.  My PC has no wifi adapter however my laptop does and my laptop can connect to the internet via wifi.  How is wifi okay yet my PC that is directly connected to the modem not okay?  I've been on hold for over an hour with Telstra.  Is this a telstra issue or something at my end? I went through all the troubleshooting tips but to no avail.

Thank you.

[Jupiter]

Your NBN cable has gone down and your Telstra modem is on LTE backup.

As far as the PC no longer connecting to the internet through the LAN port, that may have something to do with IPv4/6 settings on the Telstra modem. @cf4 has far more experience with the current Telstra modems and my be able to assist.

[Jupiter · Accepted solution]

OK. Found another post that may help.

If you log in to your modem and change the mobile backup settings so that it uses IPv4 & IPv6 instead of just IPv6 (the default).

If that still doesn't allow access via the LAN port, you can disable IPv6 on the LAN by going to  Advanced > Local Network > IPv6 state.

[cf4]

On 4G back modem is set to use IPv6. This can be changed in modem or you could enable IPv6 on the PC. See link below for how to enable IPv6.

https://appuals.com/how-to-enable-ipv6-on-a-windows-computer/

[wasteland]

Thanks @Jupiter and @cf4.  My PC was enabled to use IPv6 already, I just needed to change the mobile settings on my modem to use IPv4 and 6 instead of just IPv6.