i just got my d-link dfe-650. this is a ethernet port that you can plug into the pci slot in your laptop. i plug it in with no Ethernet plugged in and it says connected to the wired network. when i plug the ethernet into the device only one of the three lights turn on. at my house i have a cable broadband internet access.
when i am at my school i plug an Ethernet cable into it and it works automatically. is it possible that the cable could not be adaptable to the d-link dfe-650???

cable providers sometimes ( mine does ) have HW address controlled access - hence if you change machine - provider needs to reset connection for that machine to retrieve new HW address.
question is
does it work if you connect your PC directly without Dlink ??

if yes
then enter the dlink admin panel via browser and clone the HW address of the machine that is working on the connection.
that is one reason why dlink may NOT connect - i have a dlink and had exactly above problem.
if you have your dlink new - i safely assume you went thru the setup routine built in the dlink box normally ( i have a 524 ) - not sure about your 650.

other problems - may be someone else knows the solution