Error 258 when connecting to sql server instance over the network

Question

Can't connect to a sql server instance over the network, and all SSMS gives me is a 258 error.

Everything is supposed to be correct.

1. Both machines are inside a domain and the user was added to the security\logins during installation.
2. Server Authentication is set to "SQL Server and Windows Authentication mode"
3. Firewall has the following ports open: 1433, 1434, 4022, 135, 2383, & 2382 TCP, and 1434, & 1433 UDP.
4. Both "SQL Server (INSTANCE)" and "SQL Server Browser" services are running.
5. "Allow remote connections to this server" is enabled.
6. TCP/IP is enabled in Protocols for INSTANCE.

Am I missing something? I am double checking the configuration in other servers inside the network and there doesn't seem to be anything missing.

Answer 1

I managed to get it working. Named instances use dynamic ports by default. I needed to change the firewall rule so that it allows traffic for the program instead of specifying the actual ports.