Why can't I use port 1433?

I have configured SQL Server 13 to Allow Remote Connections, I've also enabled TCP/IP and verified the port specified is 1433. The computer running SQL server has the firewall disabled. I have forwarded port 1433 on my router. I can connect to the SQL server from another computer in the LAN, but not outside the LAN.

I tried changing the SQL Server TCP/IP listening port to 49172 and I was able to connect to the official site SQL server outside the LAN. Why can't I use port 1433? I've disabled every type of security option on my router. I have a Sophos UTM9 firewall/router.

  • Hi Leo,

    Have you run a packet capture on your XG WebAdmin while trying to access your SQL server externally using port 1433?

    Could you please post the output so we can analyze?