We're having really poor network performance at our office and as such, decided to upgrade our hardware. We replaced our wifi ethernet bridge, which corrected some problems, replaced our DSL modem with a newer model, but still have intermittent lags in our ATT 384K ADSL where IE or firefox stalls at "connecting ..." and then eventually loads the page or times out.

In anycase, we ordered a D-Link DSL-2640B ADSL modem with built in router and wireless access point. This is a great unit, runs a bit hot, and has quite a few advanced settings that I'm not too clear about. I've called ATT and D-link tech support but neither have the technical knowledge to answer my questions, sadly. Google seems to only yield white papers explaining the highly technical process that even I cannot understand. That said, I'm trying to figure out the difference between these two settings:

Any help on the correct settings to apply for ATT/SBC Yahoo DSL here in California, US, would be great (the unit works intermittently - I'm thinking it's because of these crazy settings)!

ATM PVC Configuration: I am allowed to choose UBR with/without PCR, CBR, realtime VBR, or non-realtime VBR. The default is UBR without PCR.

Connection Type: I know we use PPPoE, but then it provides two encapsulation types - VC/MUX or LLC/SNAP-Bridge - the DSL connection works with both, but what is the most appropriate setting? I believe my old 2wire modem had the same two settings, but I don't recall what it was.

PPP Username and Password: What is the correct authentication type? PAP, CHAP, or MSCHAP? And what is PPP IP extension? Should it be enabled/disabled?

Any explanations on this would be GREATLY appreciated!