* Not a teacher
Both could work depending on what message you want to convey. I would also use "since" instead of "from".
1) Since morning, my Internet (cable) has not been connected. (the cable was not connected, therefore the Internet connection was down - your "fault")
2) Since morning, my Internet has not been working. (the cable was connected, but there were problems with the connection (ISP issues, DNS issues etc.) - not your "fault")