I had a difficult time setting up my new OBi110 on atx2 unverse [this post only needs to be available to the OBi forum so the service provider names have been changed.]
The problem seems to be that my last available port on the router/modem was labeled "Broadband". That port may work, but I will wait for others to report success. At that point I was also manually entering the address for the Obi110. Not sure how essential these two steps are.
After I unplugged my backup computer and used a regular Internet port on the router/modem, and then powered down and back up the router/modem, I finally got it.
Hope this helps