Port mapping in Windows Server 2016 - Docker

Question

I have been trying to setup Docker in Windows Server 2016 in an AWS instance to run an IIS program.

From this question, Cannot access an IIS container from browser - Docker, IIS has been setup inside a container and it is accessible from the host without port mapping.

However, if I want to allow other users from the Internet/Intranet to access the website, after Google-ing it, I guess we do need port mapping...

The error I have encountered in port mapping is given in the above question so... I guess using nat is not the correct option. Therefore, my team and I tried to create another network (custom/bridge) following instructions from https://docs.docker.com/v17.09/engine/userguide/networking/#user-defined-networks

However, we cannot create a network as follows: ; Googled answer: https://github.com/docker/for-win/issues/1960

My team guessed maybe its because AWS blocked that option, if anyone can confirm me, please do.

Another thing that I notice is: when we create an ECS instance in AWS,

So... only default = NAT network mode is accepted in Windows server?

Our objective: put the container hosted IIS application to Internet/Intranet in Windows Server 2016...

If anyone has any suggestion/advice, please tell me, many thanks.