Can't sign in with Android

[Earl Zirkle]

Our company recently migrated from Lync 2010 to Skype for Business Server 2015.  We have 3 Enterprise pools in different regions of the world.  Our first pool is located in the US and we have a pair of reverse proxy servers that handle all mobility sign ins for all of the pools.  The Web Application Proxy servers have rules published to proxy the external web services URLs, I used the Microsoft guide.  In all regions, iPhones and Windows phones can sign in without any issues, Android phones in the US can sign in, but in other regions can not.  For one region, revoking the users' certificates worked, but for the 3rd region it does not.  As best we can tell we have all of the necessary firewall rules open.  Does anyone else here have experience with multiple pools using the Web Application Proxy servers, and Android phones?  I worked with Microsoft for about a month on this issue and we could not resolve it.  We are moving users to the cloud, and don't have the issue there.

[#2]

Anyone?

[#3]

what are the regions and where are the coming from, what countries?  If they try https://testconnectivity.microsoft.com/ from their mobile devices does it work?  What if they try the connectivity analyzer as well.  Perhaps they may have a manual configuretion setting in place?  Maybe remove the app and re-install it?

[#4]

China and Australia.  I can't remember if we tried from the mobile device.  We'll give that a shot.  We tried uninstalling and resinstalling the app.

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[#5]

Currently we have two Web Application Proxy servers that are handling the mobile and Mac devices.  They sit behind an F5.  One of them is disabled.  Both have pass-thru rules set up with External URLs TCP 443 and Backend URLs 4443.  All of the Backend URLs have hosts file entries.  I'm also using 1 NIC on the servers, they are located in a DMZ segment that has access to both the Internet and Internal network.  The proxy servers are located with Front End pool #1 in Americas, but also handle traffice for Pool #2 EMEA, and Pool #3 APAC.