Skype for business 2015

Hey All

 

We are having a set of f5 which is placed in DMZ. So it is 2 arm mode, one arm facing the internal of DMZ and other arm, going external and through the same interface it goes to the production internal network as well.

 

So , today we did the Skype for business configuration via the i app.The Skype setting has front end server .all request comes to front end server . This is my first time doing Skype.So the customer wanted reverse proxy for external connections. Also, the internal users also they want to go to f5 and then to lync server and not access directly ie while accessing via mobile phone app.

 

The external users are signing in succesfully via app. But these same user when connected via corporate network, which goes via different VIP, the signing in isn't happening. The external users come on 443 and redirects to 4443 while internal user come on 443/80 and goes into 443/80 pool respectively via different vip. On taking a tcpdump, I can see response coming back from front end server. But the user isn't able to login .from front end server to f5 snat ip, it's reachable. But sign in is unsuccessful via mobile app. we are doing Snat for traffic to internal production servers.can you guys suggest what could be going wrong?