Dsl-link light indicates your modem whether or not it can see/communicate with the exchange equipment/dslam. The reason can vary from faults on the line(joints, gremlins, isanjoka(eskom tv ad) heh etc) to your connections at your premises. Check/ensure all phones are using filters. Best way is to disconnect phones(ensures not phone calls will come in) and turn off the router. Routers are sometimes silly, anyways turn it on and see if the light gets stable. It will flash for 1 or 2 rounds so perhaps go get something to eat else you will want to do something to it.(1 - 5 minutes max).If you want try another jack. Btw make sure that the router is plugged into the wall jack and NOT into the pots filter. If you have a spare phone cable, try bypassing the lightning protection incase it is faulty. Still flashing phone then and tell them its flashing.
Things to keep in mind. Some routers use the link light to indicate activity too, like my d-link, the adsl light will flicker but one of those fast flickering so that light is more on than off. Routers vary in times taken to synch &/or the line quality come in to play too. If your filter is faulty everytime you get a call, phone rings, recieve fax/analogue things your adsl line will drop or struggle to synch. As i said some routers are just funky and sensitive.
Best way to check if its a pwd problem is to set the router to bridge mode and use win xp PPPoE client to connect. Common errors:
Error 691 -> uname/pwd is incorrect.
Error 678 -> possibly connection issue pc-to-router, router-to-exch or exch-to-network. Check that you router is set to 'bridge/1483 bridged ip LLC' else you WILL get a 678 even though the line is fine and router is working and synching. No synch/dsl link flashing will also give you this error.
Error 769 ->
your network card/modem is disabled. Go forth and enable it!
