Frequently Asked Question

Specific to 3GEN phones, when using Windows Server 2012 R2 for NTP, The
phones send a query and receive a response but will not update the time
displayed on the phone. Upon testing with Windows Server 2016, the
phones get updated and the polling intervals work correctly. With
Windows Server 2012 R2 the Polling intervals do not occur as set in the
phone Web UI.


Attached are two Wireshark captures in a Word Doc.

10.50.1.6 = Cetis 3GEN phone
10.50.0.2 = Windows 2012 R2 Server
10.0.0.55 = Windows 2016 Server

You'll see how the 3GEN phone using Windows 2012 R2 server requests once, but
does not send queries after that. Both are set to a 30 second poll.
Best solution as of 01/09/2020:
Setting the NTP server to a public server. I.e. 0.pool.ntp.orgUpgrading server to 2016 version.