Error sending stun request for calls (WebRTC)


I’m trying to use WebRTC with asterisk in my local network via SIPML5.
I have 2 registered users, 198 and 199 on two different computers and asterisk on a last computer
I did a very simple dialplan :

exten => 11,1,Dial(PJSIP/198)
same => n,Hangup()

So I can register, call, but I have no sound on each of my computers, and I have this error when i call :

So here is my neewbie question :

I can’t use WebRTC on my local network without internet? Or I missed/don’t understand something else ?

Anybody help-me? I have the same problem with sipml5 and public IP:

stun show status
Hostname Port Period Retries Status ExternAddr ExternPort
(null) 0 30 3 INIT 0

Executing [200@default:1] Progress(“PJSIP/199-00000006”, “”) in new stack
> 0x7f6e1400c160 – Strict RTP learning after remote address set to: 191.33.1X6.X6:61673
[Dec 9 11:37:29] ERROR[18938]: pjproject:0 <?>: icess0x7f6e1405cb78 …Error sending STUN request: Network is unreachable
– Executing [200@default:2] Dial(“PJSIP/199-00000006”, “PJSIP/2000”) in new stack
– Called PJSIP/2000