Hi,
Sorry for taking a little while to come back to you, I didnt receive the normal notifications.
It is not a problem I have seen before, the only thing I can think is maybe firewalls or security settings on your computer ?
When you started up the Minecraft server (or Minecraft itself) you might have been asked to allow it to access the network, if you said "dont allow", your computer might be blocking connections to it.
Are you using Windows or Mac?
Martin