If you have temporarily disabled all firewalls that you know of and continue to have this problem, then it's almost certainly a firewall that you aren't aware of.
Windows 7, 8, 10Community Q&A Your computer's clock may be as many as a few seconds to a few minutes off the correct time.
I can sync time of win7 from a ntp linux server manually.
Net Time is a Simple Network Time Protocol (SNTP) client for Windows 95/98/Me/NT/2000/XP/Vista/7/8/10 and Server 2003/2008/2012/2016.
Your current computer time is compared with the current atomic time and an adjustment is made to keep your local computer up-to-date with the exact time now.
While it is great to have this functionality in Windows, configuring this time service is painful!
In that situation it's still up to the Windows Time service when to actually performs a sync, which will be once per week.
There is a Special Poll Interval setting under HKEY_LOCAL_MACHINE\SYSTEM\Current Control Set\services\W32Time\Time Providers\Ntp Client (note: it has moved at least once between Windows versions) which is the time (in minutes) between time syncs... While modifying that registry value may update the "next sync time" displayed in the control panel, I have found it does not actually affect how often the clock is synched.
The Net Time project has been resurrected by myself, Mark Griffiths, and I'm now making an updated version available here: If you find Net Time useful, please consider making a donation to show your appreciation and to encourage further development of Net Time!
There is no way to change this interval through the user interface, it has to be done using the registry editor (regedit).
While World Time can help you look up accurate times around the world, our visitors have expressed much interest in our help to keep your local computer clock accurate, too.
Therefore, Windows 7 includes a time synchronization scheduler to synchronize your clock automatically, located on the Internet Time tab in the Date & Time Settings.
The default interval for this process is one week (which is 604,800 seconds).
I've seen suggestions that you change the existing Synchronize Time scheduled task so that it runs more often. I tried making that task run once a day and my clocks still drifted.