Stun request failed?

[Transim]

Hey folks - I'm posting here before I get myself elbows deep into our Asterisk system, because the only thing Google provides that seems to have the same issue was due to an outage with 3cx, so here goes (sorry if this has been answered, my searches haven't turned anything up): Today, out of the blue, our 3cx phone clients have been failing when they're trying to connect through our Asterisk server. The error message reported in the Debug log is: STUN request failed (about 8 times), and then the phone is left unconnected.

I suspect that this problem is external to our network, as there have been no major changes (or even minor ones, really) for the last 3 weeks, and phones that were able to connect earlier today are suddenly unable to. DNS seems to resolve to stun.3cx.com, however the ping fails (although they may have ICMP responses disabled, so this may not be significant).

In short - nothing has changed for us that we're aware of...is there a problem on the 3cx side? Something I can tell my users? Is there anything that I can do on my end to bypass this requirement? (as I said, the system has been working with it's current configuration for over a year...I don't think it's us).

Thanks for the help!
James

 

[ian.watts]

Do yourself a favor with some "network magic", use DNS.

I suffered for half a day before finding and testing a STUN client to identify other STUN servers in the wild while the 3CX STUN servers were unavailable.

From there, I aliased stun.<me...> in DNS, and pointed all phones which need STUN to that.
If/when something goes awry, I just change that alias to point to an alive STUN host.. done.
In fact, as an MSP, I just aliased stun.<clientdomain> to stun.<me>.. which is then aliased.. so I just change it once instead of fifteen times.. or get granular/particular as needed.

That being said, stun3.3cx.com is responding to STUN requests as of this post.. go with it if you will, or better, CNAME stun.<you> to that and use your alias.