I notice that port 80 is not in your list. Normally, that would be the default web (http) port.
Port 8080, however, is open. This is a common place to park a secondary web server or proxy.
Try:
Of course, I forgot your device IP, but you get the idea.
The DEV page is no longer a basic html page you can open in your browser. It expects specific parameters and an upload package, so you have to use curl to format a GET request that it can do something with.
More details here at the bottom of:
See https://blog.roku.com/developer/2013/10/08/security-enhancements-added-to-channel-development
