The ISP could be filtering MAC addresses "denying connectivity" through the ethernet port of the modem. Call your ISP and ask them if they can reprovission your modem and DHCP. Follow their instructions to the letter. You may want go into the computer network connection properties and either "rebuild" the connection, or completely uninstall and re-install the hardware/drivers and reconfigure the connection from scratch prior to contacting your ISP. Cause if you don't and they have any "question" as to the proper function of your pc they may try to insist that they come out and LOOK at your pc, mostly to try and get you to PAY them for servicing your PC..... even though it may or may not need service...