I have a Lync 2013 FE and Edge working to provide federated Lync service to our domain. Internal/External chat works fine but when getting on a video call with someone outside of the LAN the call will go through, video and audio, until 10 seconds have passed and the call is dropped. It is consistently 10 seconds every time and I don't know where to start in troubleshooting this.
Lync 2013 external video calls drop after 10 seconds
lynclync-2013
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I have had the same experience trying to connect a CX600 that has never connected to a Lync server. I have used Jeff Schertz's Blog extensively in an effort to configure this.
http://blog.schertz.name/2013/05/updating-lync-phone-edition-devices-lync-2013/
I too noticed the VLAN ID of 1 (default) and found a post by Jeff on how to set this for Lync. However I did not have success with this, once configured per the Blog entry, the phone could no longer get an IP address from DHCP. What we did see was that based on the error code the phone listed, 2f0d, the issue seemed to have something to do with Lync not trusting our private CA. We tried swapping out our private cert for a wildcard cert issued by CA that is trusted by Lync and were then able to connect to our Lync server and the phone updated to the latest firmware after a few minutes.
As I've read a number of post telling that wildcards will not work, it was a surprise to us that this was the work around. We'd like to use the private cert, but have not found a way to do it yet.
Based on your information you shared so far there seamed to be an issue with the Lync Webservices running on the FrontendServer. As we do not know your topology in more details its hard to find the issue with so less information, but I will try to help:
You must have defined a URL for web services (see here for more infos). This should point to your Reverse Proxy (for more infos see here), the reverse proxy should forward the traffic on 443/80 he got to the internal frondend server on 4443/8080 (that depends on your topology). It looks like something isn´t working here. Additional make sure you configured the "Forward the host header" option correctly as explained here.
P.S. For further troubleshooting you can install Fiddler and check which URLs the client try to open and if you see more inside fiddler.
Update:
Just for completeness: There is an change in the may .net Framework which might cause that kind of issue. You can disable this feature or use a proper SSL certificate. More info's can be found here.
Best Answer
I had exactly the same and for my environment incoming connections on UDP 3478 and TCP 443 wasn't working due to a temp. block via a firewall feature (aggressive line aging).