This is on Windows.
I've also tried the machine's IP instead of the * in the url/address.

I did another test with NetCat, listening on my local machine and sending a request from outside through the public IP to that same port 45050 and it all works fine.
So the problem is 100% coming from cpprestsdk.

Is there anyway to get more verbose debug infos or anything useful out of it?

I am running into similar issue.Host name set to 'LocalHost' works fine. setting host={machinename} starts listener but request doesn't happen and instead get error 'connect ECONNREFUSED'.
If Host is set to an IP address exception occurs while opening listener.
Getting this issue fixed quickly is crucial else it makes all the efforts halted.

	uri_builder uri;
	uri.set_scheme(U("http"));
	uri.set_host(U("+"));
	uri.set_port(U("80"));
	uri.set_path(U("/api/"));

http_listener listener(uri.to_uri());

This, and ONLY this is working. I cannot explain it myself, but that's how it is.
ONLY the strong wildcard works, nothing else. https://docs.microsoft.com/de-de/windows/win32/http/urlprefix-strings
It ONLY works when I use port 80. I can forward from my router from whatever port I want at the exernal IP to that 80 on the machine that runs the server and only then it succeeds.
it ONLY works when there is a path set up. If I choose to just use "/" , it does not work.

Oh and it ofcourse only works on a freshly setup windows server 2019, on my windows 10 I get a nice exception from the HttpAddUrlToUrlGroup call:

HTTP Exception: Error adding url to url group, 
Error: 1214, The format of the specified network name is invalid.

why 🤷 ?

So regarding the error on my win10 system, I fixed it by checking
netsh http show iplisten
and then removing the one which was listed there.

Thank you fxfire that worked for me as well.

After 3 days of wasting my time on something so basic, I finally found a solution in some dark area of the internet:

Since the HTTP Server API internally uses a kernel module http.sys, the C++ REST SDK service program is not the same as the normal TCP service program through the Windows Firewall. It is invalid to directly use the executable file of the program to establish the firewall rules. The correct way is to create a new inbound rule, set the program name to system, and set the local port to the port number you want to listen to.

This information is so important for Windows users, it should literally be NAILED ontop of the github wiki.

@fxfire Hi there. I just encounter this problem but this code

web::uri_builder uri;
    uri.set_scheme(U("http"));
    uri.set_host(U("13.59.255.62"));
    uri.set_port(U("80"));
    uri.set_path(U("/api/"));

not working for me, and i create inbound rule but i dont realy understand why you need to change name of the app ?
this method dont working either. Can you explain a bit more clear what you do for make things work ?
I trying to open server on the amazon ec2 btw.