Internet Connectivity Problem/DSL

Initially posted this in Hardware but seems a better fit here. Any and all help appreciated!

I used to have DSL with no connectivity problems, then traded the DSL for Cable, again with no issues. I recently gave my computer to family and they have decided to go with DSL but now we have had no luck with connecting to the internet through the modem (wired). They have a laptop that connects through the same modem, using the same cable, with no problem.

Can anyone give me troubleshooting tips? Bad card? Software settings changed when I switched to cable?

Thanks in advance for the help.............