You can not connect to mapped IP address within container host itself. it’s bug in Windows implementation of WinNAT. You need get private IP address of container and connect to it using port number.
Or you can access through public mapped port from another host on the same network, that shall work.
Also stop using netstat for anything. The way to go is super powerfull Get-nettcconnection
Get-NetTCPConnection -LocalPort 80