Connection between Android app and web page WebGL

Hi
I'm having some problems to connect between an Android app and th same application compiled in WebGL and loaded inside a web page. Same project made with Unity, and both are using UDP. There's something security-firewall-closed ports-setting that I have to keep in mind?
Strangely (for me) I have no problem between multiple WebGL app on different pc's.
I can exploit more information if someone ran against the same problem.

Thanks
Paolo