I use an old Motorola SBG900 cable modem to connect to the Internet via Comcast. A few weeks ago, I became unable to connect to either my email service provider's SMTP server or Comcast's SMTP server, so unable to send email, although I was able to connect to the incoming servers and receive email. At the same time I was trying to connect an Apple TV, which apparently was also unable to connect to a time server. The problem was solved by turning the SBG900's internal firewall OFF. Even the standard LOW security policy setting brought the problem back. I am using port 1111 for outgoing email to my ESP but I have no idea what ports Apple TV uses.
If anyone out there is familiar with the Motorola firewall, and can suggest any CUSTOM settings that might help, it would be very appreciated. Thanks...