Things which can break Lync desktop sharing

Question

Proxy URL filter
For one of my customers, Lync desktop sharing suddenly stopped working only from a particular network. All required ports were opened, telnet , tracert all fine, also sometimes we saw it working , so it was intermittent.  you can guess what security
and network team will say J.
Then captured traffic in netmon and it shows that there is reset for 443 traffic and uccplog shows error which points to 443 inspection device on the network , so shared it with network and security team, you wouldn’t guess their response this time
J they asked me to identify the device which is resetting 443 session.  Now I only had to solve this issue, I knew even PSS engineer can only tell us that there is reset.
I started off with question  How it works some times?” , answer to this is that whenever it worked someone from Local IT team has logged in to that computer, also when logged in as normal users netstat shows time wait for 443 and sometimes sharing invitation
expires.  This gave me a clue, so I asked for a new laptop which is not a member of any domain and started drilling down. ..Finally found that URL filtering rule has been applied to users in that subnet and corp application FQDNs are not bypassed. It
was URL filtering application which was stopping this traffic.
I told security team that proxy is causing this issue GUESS WHAT they asked me why they were not informed about Lync FQDN earlier
J
WAN optimizer.
It was another lovely day in office talking all important topics like work life balance, movies , next best weekend place etc… suddenly tickets started flowing for desktop sharing issue. Immediately P1 case was opened and all of us specialist joined P1 bridge
just to say WE DID NOT DO ANY CHANGES! Now someone is surely jealous of someone being happy or someone has not followed the change process. Who it is? And what it is has to be investigated, of course  by Lync team.
Again netmon says 443 rest and error message says 443 inspection.. Being a Microsoft application  expert you are not done yet without finding out which device is doing it, isn’t  it? . So started isolating the issue. Noticed that issue is happening
only from specific region only. So asked everyone on call what is so special about this region…there was a dead silence and there was a smart answer YOU TELL US! Well this went on for a while till someone from network team asked with low tone
will wan  optimizer has any impact on Lync traffic??
J
It was WAN optimizer which was causing this issue.
Regards
Praveen R

Answer 1

Thanks for sharing your experience. This is what the case with all of us serving this technology.
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