Error sending stun request

i have followed this tutorial [WebRTC tutorial using SIPML5]
(WebRTC tutorial using SIPML5 - Asterisk Project - Asterisk Project Wiki)
and getting this error
ERROR[55233]: pjproject: <?>: icess0x7f70f0057b58 …Error sending STUN request: Network is unreachable
call is getting establish but no sound

This is generally normal, and is seen when the machine Asterisk is on has a link local IPv6 address and the remote side provides IPv6 ICE candidates.

What is the actual network arrangement? Are you behind NAT? What is the SIP trace (pjsip set logger on)?

I should also add my standard - if you plan on deploying WebRTC at all, you need to learn about the elements it is built on (ICE, STUN, TURN, DTLS-SRTP, SIP). It can, and will, not work and relying on others to diagnose is not a good long term plan.