There are a few possibilities for what could be wrong if EndNote cannot find the host:
The domain name specified in the connection file is wrong.
Your network software does not have the correct address for the Domain Name Server.
Your Domain Name Server is not working.
If the connection file has worked in the past, the problem may lie with the Domain Name Server. If you have just made the connection file yourself and it’s never worked before, you probably entered the wrong Server Address.
If you suspect problems with the Domain Name Server, contact your network administrator.