Dotnet ef database update error: 26 - Error Locating Server/Instance Specified. How to decide?

Question

ASP.NET

I ran into a problem, with a database update, this is the error. The fact is that with SQL Management Studio, I can log into this server, both with SQL authorization and with Windows.
I saw answers on other forums, changed the configs in the services, it does not help.
Connection String :
"ConnectionString": "Data Source=olegFPC\\SQLSERVER; Database=MyDb; Persist Security Info=false; User ID='sadf'; Password='sadf'; MultipleActiveResultSets=True; Trusted_Connection=False;"

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: 26 - Error Locating Server/Instance Specified)

Answer 1

Instead of the server name, specify ip, the default instance does not need to be specified through a slash. Specify the allowed protocols in the client library settings in the control panel. If it doesn't work, write an exception, we'll think of something

Answer 2

Web application on Asp Net Core 3.1, and EFCore