I have been having some internet troubles at home (ADSL2+ connection in Australia). We get random drop-outs from the authentication connection. It will keep the connection to the DSL service, but we lose authentication and either have to restart the router/modem (its combined, a Belkin one, not sure on model number) or unplug the phone cable, wait about 30 seconds and plug it in again.

I've called the ISP (Telstra) a few times, but they only offer limited support when we dont use their supported hardware. Apparently something had happened on their side, they checked the box again (at least it sounded that simple), and told me it would be fine.

It wasnt.

I've replaced all the filters around the house, but that didnt help either. We do live a little bit away from the exchange (get a sync speed of about 3000/900), so I thought it could be due to line noise but that hasnt helped.

Telstra allow both PPPoE and PPPoA connections (which I'm configuring through my router, dont have software on the PC side). I've been running PPPoA the whole time, would it make any difference changing it to PPPoE?

If not, are there any other theories as to why we would be experiencing these drop-outs? It has been fine for at least 12 months, then suddenly started about 2 months ago.