What is an easy method to test whether UDP traffic is blocked? What is an easy method for an Android device to tell whether a data connection (either WiFi or mobile data alone) has UDP traffic blocked? Many corporate and public access points restrict UDP access, and I am looking for a way to detect this manually. I am interested in this because real-time VOIP applications, for example, should not be expected to work with the same performance on TCP as on UDP.

For the purposes of this question, I would assume that the data connection is either:


using hole-punching or 
blocks all UDP traffic that is not DNS-related. 


Also, please assume the Android device is not rooted.
You can check if UDP traffic is blocked with this app:

https://play.google.com/store/apps/details?id=be.ac.ulg.mobiletracebox

It's free and it works on not rooted devices.

Just select UDP category and run the test. 

To check if UDP traffic is blocked only on certain ports you can use "Advanced" to set Destination Port (along with other fields of the packet).

I'm affiliated with developers of this app, but frankly I don't know any "famous" app doing the same job.