MQL5 SocketConnect fails with error 4014 connecting to local TCP server

I’m developing an MQL5 Expert Advisor that should connect to a local TCP server (127.0.0.1:5001). The server is running and responds correctly to Telnet. In MetaTrader, I added 127.0.0.1:5001 in Options → Expert Advisors → Allow WebRequest for listed URLs. Firewall is disabled, and the port is free.

My MQL5 code is:

int socket;

int OnInit()
{
    socket = SocketCreate();
    if(socket == INVALID_HANDLE)
    {
        Print("SocketCreate failed");
        return(INIT_FAILED);
    }

    if(!SocketConnect(socket, "127.0.0.1", 5001))
    {
        Print("SocketConnect failed with error: ", GetLastError());
        return(INIT_FAILED);
    }

    Print("Connected successfully");
    return(INIT_SUCCEEDED);
}

void OnDeinit(const int reason)
{
    SocketClose(socket);
}

Tests I have done:

• Verified the server is listening and reachable with Telnet.
• Confirmed the port (5001) is open and available.
• Disabled firewall completely.
• Used numeric IP 127.0.0.1.
• Added 127.0.0.1:5001 to Metatrader Expert Advisors options.
• Tried creating a TCP server using Netcat (nc -l 5001), but MQL5 still fails with error 4014.

Question Has anyone implemented a minimal TCP server for MQL5 testing or has a working configuration example? I want to understand whether the issue is on the MQL5 side or the server side. Any example code or demo would be greatly appreciated.