If I understand your question correctly, in order to connect from remote PC to the SQL Server you need to know the IP address where the server resides and the port the SQL Server is using. For the syntax of the connection string using IP address, have a look at
Connect via an IP address - SqlConnection - ConnectionStrings.com[
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Ensure that communication between the computers is allowed using that port so that for example firewalls do not block it. Another thing is that if you're using public networks, the traffic can be seen and the the SQL Server is available in public so I suggest for example using VPN in such case and blocking all access to SQL Server from outside world.