WebRTC dtls errors when sender and receiver are on different networks.

[Nirbheek Chauhan]

On Tue, Oct 23, 2018 at 10:27 AM Mandar Joshi <emailmandar at gmail.com> wrote:
> I've narrowed down the problem further.
> I'm doing all testing using Nirbheek's gstwebrtc-demo sendrecv C demo
> with webrtc.nirbheek.in
>
> Here is the log when webrtc.nirbheek.in is opened on Android's Chrome
> browser https://pastebin.com/Kp1xFjn1 (This works)
> and here is the log when it's opened on a USB tethered Chrome browser
> https://pastebin.com/1wqyC0Nr (Doesn't Work)
>
> libnice debug log doesn't show any inbound STUN packets after the
> STUN-CC REQ message in the second case.
>

In all likelihood the NAT used by the USB tethering on your phone
doesn't support STUN. Check chrome://webrtc-internals on the browser,
and compare with how, say, appear.in works.

In any case, you almost always want to setup your own TURN server for
cases where STUN cannot succeed and set that in the configuration.

Cheers,
Nirbheek