Error: 50 when publishing asp.net application on local IIS

Hello,
 
I need to have my web application to be accessible on local network. I followed these two articles for publishing my web application on local IIS.
 
http://www.c-sharpcorner.com/uploadfile/francissvk/how-to-publish-asp-net-web-application-using-visual-studio-2/
 
http://www.c-sharpcorner.com/uploadfile/11d5d2/how-to-deploy-asp-net-website-in-iis-on-localhost/ 
 
My problem is that I get the following error:
 
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 instance name is correct and that SQL Server is configured to allow remote connections. (provider: SQL Network Interfaces, error: 50 - Local Database Runtime error occurred. Cannot create an automatic instance. See the Windows Application event log for error details.)
 
I'm using SQL Server 2014 express edition. Note that the application is fully functioning when I run it from VS 2015 on the same machine.
 
What I did so far:
1. Check SQL Server remote connections and are enable.
2. Enable TCP/IP on SQL Server Configuration
3. Open port 1433 for inbound/outbound connections. 
 
I also get the following message when I test the connection of the application on IIS.
 
The server is configured to use pass-through authentication with a built-in account to access the specified physical path. However, IIS Manager cannot verify whether the built-in account has access. Make sure that the application pool identity has Read access to the physical path. If this server is joined to a domain, and the application pool identity is NetworkService or LocalSystem, verify that \$ has Read access to the physical path. Then test these settings again.