I’m running piaware and I can get the raw data (ports 30003 et all) on the same pi (usng wget), but when I try to read them from my laptop thru a browser (chrome, edge, firefox, IE) I get and “invalid response” error (ie. http://192.168.0.231:30003/)
The laptop is in the same home network and I can access the pi to see Skyview, Tar1090, Graphs1090 and Timelapse without any problem. (ie. http://192.168.0.231/dump1090-fa/)
30003 is normally a TCP port that does not run http.
You may be able to telnet to the port to see data, however, I doubt it would work in a browser.
Firefox Ver. 84.0.2 64bit works for me ok. (The others return an error)
It works within a browser in another Pi (same network) but not on the laptops.
I accessed each of my 6 RPi’s port 30003 from my Windows 10 notebook using FF 84.0.2.
In addition I accessed the RPi port 3003 from outside my local network using a route from the US to Denmark to Germany to the RPi in the US.
It is an invalid response as it’s just TCP.
Use a suitable application to access it … not sure what is good on windows.
Install WSL Ubuntu or something (windows subsystem for linux) and use socat 
Anyhow telnet might work.
telnet works from my Windows 10 FF browser. telnet://192.168.x.x:30003
