Connecting to a local SQL server from a website

We have a small network behind a firewall (WatchGuard XTM 2 series) and network switch. On our network we have multiple instances of SQL server, but 1 in specific that I would like to be able to access remotely from our website. We have a static IP address from our ISP and then all the machines on the network have a locally assigned dynamic IP address. When trying to connect to the database from outside our network how do I get the request to be directed to the proper machine / SQL instance? Is it a parameter in my connection string or something in my firewall?

A few things to rule out:

1) The firewall is allowing access from the website to our network. I added the site's IP and opened up port 1433. Also, when trying to connect and monitoring the firewall no exceptions come up as they did before I added the proper IP address.

2) Remote connections on the SQL server has been setup and enabled. I've done a lot of reading up on remote connections and I am sure it has been setup properly.

I am currently getting this error message on my site:

A network-related or instance-specific error occurred while establishing a connection to SQL Server. The server was not found or was not accessible. Verify that the开发者_运维知识库 instance name is correct and that SQL Server is configured to allow remote connections. (provider: TCP Provider, error: 0 - A connection attempt failed because the connected party did not properly respond after a period of time, or established connection failed because connected host has failed to respond.)

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The Server parameter of the ConnectionString indicates what server to connect to. Assign an ip address or URL to the server that you want to access and put that in your connection string.