Postman can't connect to Docker container on Windows

Question

Windows 10 with all latest Windows Update. No commercial anti-virus/malware or firewall installed. Running Windows Defender out-of-the-box.

Visual Studio 2022 with all latest updates.

Docker Desktop for Windows will all latest updates.

Postman with all latest updates.

I have a Visual Studio 2022 ASP.NET Core Web API project that's enabled for Docker.

I Start Debugging and I see in Docker Desktop For Windows that a container is started.

49155:443
49156:80

In Windows PowerShell I can successfully test.network connectivity:

Test-NetConnection localhost -Port 49155

ComputerName     : localhost
RemoteAddress    : ::1
RemotePort       : 49155
InterfaceAlias   : Loopback Pseudo-Interface 1
SourceAddress    : ::1
TcpTestSucceeded : True

However if I send a request via Postman it's unable to connect.

GET https://localhost:49155/api/stocks/get
Error: Client network socket disconnected before secure TLS connection was established

I'm not on a VPN and I'm not using a proxy.

Start > Internet Options > Connections > LAN Settings > proxy server unchecked

Postman Settings: all proxy checkboxes unchecked, SSL Certificate Verification set to off.

Answer 1

HTTPS/TLS connections require the client and server to have TLS cipher suites in common and a valid certificate that the client trusts on the server. Powershell Test-NetConnection only validates the TCP socket, not the TLS connection.

You need to tell Postman to ignore TLS (AKA SSL) warnings. There's a setting to do that, but per How to turn off all SSL checks on Postman for a specific site? it may not be available depending on where you got Postman from.