Update 2017/09/12 – Added SfB2016 MSI ( 16.0.4588.1001 ). We had some reports that when trying to sign in to Skype for Business Online users were experiencing delays during the sign in process. This behavior was related to environments were the Lync/SfB client is configured to use a Proxy Server to connect to the Skype for Business Online servers.
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After researching the delay was occurring because the client was trying establish a direct connection and only after that connection timed out it would try to connect using the configured Proxy Server: As a workaround we could configure the Firewalls to send RESET Packets and the Lync/SfB client won’t wait for the connection attempt to timeout. Samsung S5282 Full Flash File.