1. How are you connected? Mac > TC > Modem?
2. If so what modem is facing the internet?
3. What are the security settings on the modem? For my Comcast Arris modem I have 3 security levels. I fail the Shields Up! website port scan on low and medium. However I can fix medium by disabling device discovery. Your scan is much more rigorous, so I just use this as an example.
4. What happens if you run the scan with the modem on but nothing connected to it?
5. If (4) is fine, what happens if you connect the TC?
6. If (5) is fine, then the computer?
7. If (6) is fine, any other devices connected to the modem?