Last week, and then earlier today, our network connection would suddenly stop working. It appeared that all incoming connections would timeout, and all outbound connections would never receive responses. The other interesting fact, was that our Vonage ATA, which had a different ip address was working fine.
It looks like the problem was that there was another computer on the
subnet that had the same ip address. Once I changed the ip address,
everything is working fine. This makes me think that it would be good
to get a routable block of ip address. Then it should be less likely
that there will be a conflicting ip address.