I have seen this problem in a couple of deployments now and have decided to share this information since there is not much about it on the web.
The problem
Event ID 41024 – Lost connection to all Web Conferencing Edge Services
Event ID 41024 – Lost connection to the Web Conferencing Edge Server
Event ID 41025 – Connection to the Web Conferencing Edge Server has been restored
These Event ID’s appears every five minutes on the Lync Front End Server, but not in all implementations. I don’t know why it is in only some implementations.
The Resolution
Disable IPv6 on the Front End server. When implementing Exchange 2007 and 2010 we often came across a similar problem where the resolution was to disable IPv6. Disabling IPv6 has cleared the Event ID errors in the cases I have seen. To disable IPv6 properly don’t just uncheck IPv6 on the network adapter, but do it in registry and reboot. See this KB article for how to disable IPv6 properly: http://support.microsoft.com/kb/929852
Screens of the exact Event ID’s
msunified.net 
Thanks Ståle!
Thank you for this info! I was going crazy (smile) until I read this and resolved it per the kb article referenced.
[…] Lync Server Front End: Lost connection to the Web Conferencing Edge Server: https://msunified.net/2011/02/09/lync-server-front-end-lost-connection-to-the-web-conferencing-edge-s… […]
Hi, thanks for the hint. That didn’t worked in my environment, IPv6 was already completely disabled. But now I moved the “internal” network adapter on top of the network binding order and rebooted. The events are gone now and conferencing works perfect.
Ok, thanks for posting it in the article :) It was an the EDGE server you did this I take it?
It was the edge, Sorry for The laaaate response :-)
Stale,
You saved my life. Thanks bro. We were about to take off after the firewall guys with knives pulled when I found your blog. It was probably a mixture of YOUR article mixed with Wolfgangs post that helped me. My bindings were all screwed up on my edge servers and I was getting the exact error you mentioned. Once I verified that IPV6 was off (and it was) and I adjusted the bindings (per Wolfgang) … I restarted the edge services and noticed that the error persisted … and to my terror presence for federated users was broken. I then restarted 1 WFE server and it cleared up on that server. I restarted the other WFE and it was completely clear on both servers. Presence picked back up and started working and I then immediately did a test call and it worked perfectly along with whiteboard, poll, etc.
Glad my article could help you on the right track of your solution. Thanks for posting :)
[…] Note. I’ve run into some strange issues that seem to relate to IPv6 being enabled on the Front-End Server. For more information check this blog from Ståle Hansen: https://msunified.net/2011/02/09/lync-server-front-end-lost-connection-to-the-web-conferencing-edge-s… […]
[…] Note. I’ve run into some strange issues that seem to relate to IPv6 being enabled on the Front-End Server. For more information check this blog from Ståle Hansen: https://msunified.net/2011/02/09/lync-server-front-end-lost-connection-to-the-web-conferencing-edge-s… […]