Just changed from ADSL to NBN, had usual problem was set up for static IP and modem was not, took two weeks to fix.
Now often when I power my computer up it indicates I am connected to internet but I cannot access any sites, Microsoft diags tell me there is no IP address and sometimes can reset this. Optus tech checked things out and said problems was between my computer and the Sagemcom modem, tried 2 modems similar problems, no previous problems on ADSL. Any advice would be appreciated as this has now been going on for over 4 weeks. Going to 3rd party modem is not an option as I need Voip.
I am assuming when you mention Static IP, you are referring to the static IP of your PC and not the Static IP of the Optus WAN IP? Are all of your devices prevented from using the Internet or is it just your PC?
Is your modem set for IPoE/Dynamic WAN IP/No User ID & Password required or is it set to the old ADSL PPPoE Authenication Setting - User ID& password required. With NBN, I think you need it to be on IPoE which generally does not require a User ID or Password - so if set to PPPoE, try blanking out your User ID & Password. Not sure if that would make any difference - Optus may ignore your authenication information if it was set up per your ADSL configuration or it may confuse the Optus/NBN Network if left on.
If you are using a Windows PC, can you get into the Command App, cmd screen, and type ipconfig/all.
You should see your fixed LAN/Wi-Fi PC IP address which must be in the same range as your Modem's Gateway IP Address listed there and also see the Primary and Secondary DNS Servers that your PC has been programmed to use. I would expect these addresses to be consistent with the embedded DNS addresses in the Sagemcom Modem which are set and not changeable in default. These should correlate to the National or State Optus published DNS Server addresses. Changes to the DNS settings in the Modem are not possible in the standard customer User Admin Mode of the Advanced Settings. If all good there, have you tried clearing out your Data Cache in the Web Browser?