Mac Pro won't connect to Ethernet

My Mac Pro will not connect to the internet, but it connects to Wifi via my comcast modem.
the modem was switched out today, but I couldn't connect before that - which is why they came and replaced my modem.
The lights in the Diagnostics window say:
Ethernet: connected
Wifi: connected
ISP: Fail
Internet: Fail
Server: Fail
Any ideas?


Boot into Recovery by holding down the key combination command-R at the startup chime. Release the keys when you see a gray screen with a spinning dial.
Note: You need an always-on Ethernet or Wi-Fi connection to the Internet to use Recovery. It won’t work with USB or PPPoE modems, or with proxy servers, or with networks that require a certificate for authentication.
From the OS X Utilities screen, select Get Help Online. A clean copy of Safari will launch. No plugins, such as Flash, will be available. While in Recovery, you'll have no access to your saved bookmarks or passwords, so make a note of those before you begin, if they're needed for the test.
Test. After testing, reboot as usual and post the results.