Ssl – How to see when a SQL Server 2008 Certificate Object Expires (& other properties)

Check with your CoLo provider, they may be blocking access to port 1433. Many CoLos started doing this after the SQL Slammer went around a while back.

It's also recommended that you not try and access SQL Server's directly over the internet. Instead setup a VPN between the CoLo and your office and access the servers over this secure connection instead of over the public internet.

You are following the right steps (http://support.microsoft.com/kb/316898/en-us), but the error likely means that you either have no enterprise certificate authority (CA) in the domain, or the CA is not accepting new certificate requests for some reason. It may also be that your installed CA is not allowing generation of "Computer" certificate types. This can be checked in the CA configuration.

The solution depends on whether you already have an enterprise CA set up and configured. If not then you need to create one (there is guidance on the Microsoft technet site, but it's not trivial) or else use another way of generating self-signed SSL certificates such as one of the free downloadable tools.