In general the way that works is user navigates to http://contoso.com which implicitly uses port 80. Contoso server/cdn listening on port 80 redirects them through whatever means to https://contoso.com which implicitly uses 443.
I don't see value on both being on the same port. Why would I ever want to support this when the http: or https: essentially defines the default port.
Now ofcourse someone could go to http://contoso.com:443, but WHY would they do this. Again, failing to see a reason for this.
The "why/value" is usually in clearly handling accidents in hardcoding connection info, particularly for local API/webdev environments where you might pass connection information as an object/list of parameters rather than normal user focused browser URL bar entry. The upside is a connection error can be a bit more opaque than an explicit 400 or 302 saying what happened or where to go instead. That's the entire reason webservers tend to respond with an HTTP 400 in such scenarios in the first place.
Like I said though, once I remembered this was more a "hacky" type solution to give an error than built-in protocol upgrade functionality I'm not so sure the small amount of juice would actually be worth the relatively complicated squeeze for such a tool anymore.
In general the way that works is user navigates to http://contoso.com which implicitly uses port 80. Contoso server/cdn listening on port 80 redirects them through whatever means to https://contoso.com which implicitly uses 443.
I don't see value on both being on the same port. Why would I ever want to support this when the http: or https: essentially defines the default port.
Now ofcourse someone could go to http://contoso.com:443, but WHY would they do this. Again, failing to see a reason for this.