The new update introduced some additional complexity to running a DayZ server. There are some servers will configuration issues that cause them to not be able to connect to the central server.
Nearly always this is because of a particular operating system configuration (lacking updates). More rarely it is because the server had not been whitelisted or it has issues in its mission/setting configuration. Our QA are currently auditing all servers, making a list of problem ones, then Brian is going through with the server hosting owners to verify why the servers are not connecting correctly.
Please note that we cannot directly control server hosting configuration. We cannot "fix" problems associated with operating systems or incorrect server configuration. We are working with hosting providers to notify them when we identify this. If you have a problem with a server, you need to let us know the name/IP of the server. I have hundreds of people complaining about servers to me, but not one single time has someone actually told me the server.
Nearly all Hardcore servers have been audited, Regular ones are in progress.
The following is a WIP list of servers known to be experiencing connection issues.