Basic DSL Troubleshooting

Authentication Failed
Check profile and fix the user name/password accordingly.

Timeout errors
Check the DSL Modem (i.e.; Bridge, CPE, Router)
Check for sync (see below)
Ping the NIC and Router
Remove and re-install PPPoE Software

User has sync
If you have a steady green sync light, make sure you have thoroughly tech'd your computer, cables, and router/modem, including re-installing software as the problem is most likely (but not always) on your end.
If user can ping the router, then he probably just needs to remove and re-install the PPPoE software.
*One note about the Flowpoint 2100 and a common mistake people make. This router will show sync and you can ping it too, even though the cable from the computer to the router is plugged into the Console port. Most ISPs don't use the Console port for consumer DSL service. Make sure this cable is plugged into the 10BASE-T port.

User does not have sync
Check with the ISP to see if they are experiencing known outages. If the user does not have a steady green sync light, cold boot the router (at least 30-60 seconds off), and warm boot the computer. While the router is off, verify that both cables coming from the router are tightly connected at each end, and that they are using the correct cables. If sync is still not present, contact the ISP.  *The SpeedStream 4060 will not show sync unless the drivers for it are properly installed first.

If the user has sync problems, especially intermittent sync problems, check for interference from:
Halogen lamps
Fluorescent lights
Scanners
900 MHz cordless phones
Cell Phones
Ham & CB radios
AM radios  see also:
Electrical interference (don't put the router near a UPS or motor driven device)
Modem, fax, or other device on the line
Microwave oven
Shoddy phone cord
Home security/Alarm system

Has the User moved the computer or router?
Were filters installed on each phone except the DSL line? If not, does the user have a splitter at the NID? If they are using filters at each phone, they must remove the filter on the line using the DSL. If they are using a splitter at the NID, then they must use the line originally set up for DSL.

User is getting error messages
Consult the Errors page for known errors and fixes.

Slowness/Packet Loss
DSL is a best-effort service and anything 256k or above is considered acceptable. If the user is getting less than 256k, the ISP/technician should run a traceroute program to see if problems can be found where the slowness is occurring. If the problem is with the telephone company/ILEC (Covad, BellSouth, Verizon, Ameritech, etc.), then the user should contact the ISP for them to verify the line; or if the problem is with the ISP, for them to contact their Network Operating Center. If the ISP doesn't see any evidence of slowness in the traceroute, the user may be suffering from interference, etc - troubleshoot it the same way you would a sync problem. Do not assume the user just needs to modify the MTU settings to improve throughput. Consult the Tips page before changing anything in the registry.

Who Do You Complain To?

To lodge a serious complaint about a Telephone Company (Telco) or an ISP (or CLEC), your two forms of attack are the Better Business Bureau (BBB) and the Public Service Commission (PSC) for your state.
Read about the BBB on their home page. ISPs that are not going out of business hate the BBB and try hard to resolve issues that get raised there.
The PSC is the only body your Telco is afraid of. Use them if normal dispute resolution is getting you nowhere. Again, your state PSC home page should provide current information on how to lodge a complaint.

You can also use the FCC Complaint Form as well.