I found a fix for apparent NTP server breakage in Windows 11 22H2

I wasn’t sure where else (e.g. which other sites) I could’ve shared this info on, but I had noticed something in the past few weeks that I wanted to share, in the off-chance that anyone else out there had the same problem:

Starting in early April 2023, Meinberg NTP seemed to break on Windows 11 22H2 after installing monthly Windows updates, possibly KB2565063: The server service would run for an hour after system startup, and then stop and refuse to start again no matter what. The only thing that seemed to get the service running again, was either constant system restarts (Obviously a very impractical thing to do), uninstalling recent Windows updates (if Windows 11 even wanted to let me do that), or an in-place upgrade (that made Windows complain my system was becoming outdated).

The logger seemed to show NTP trying to listen to so many IPv6 addresses (e.g. ntpd[(...)]: Listen normally on 916 Ethernet [2001:(...)) that it’d hit a max limit at 1024 addresses, throw a “Can’t add socket to i/o completion port: no receive buffer: Overlapped I/O action is ongoing”, and instantly stop the service again.

This morning I finally found what seems to be a fix: To explicitly specify interface listen addresses in ntp.conf. For example:

interface listen
interface listen
interface listen (LAN address, e.g.
interface listen (The system's IPv6 public address if applicable)

So now my NTP Pool server is once more ready to face the future in operative condition.

Please consider filing a bug report at https://bugs.ntp.org so we can track down the issue. If you would like to explore the issue privately before filing a report, contact me at hart@ntp.org or davehart@gmail.com. I’m running Win11 22H2 with ntpd and not seeing the same issue. I’ve been running self-compiled ntpd for the most part, but I just switched back to the stock Meinberg 4.2.8p15 binaries dated 2021-02-22 and see only expected interface listens without any -I/–interface on the command line or interface/nic directives in ntp.conf.

Attempting to create an account on Create a new Bugzilla account gives me the error message “User account creation has been restricted. Contact your administrator or the maintainer (justdave@bugzilla.org) for information about creating an account.”

I also ended up having to uninstall KB2565063 KB5025239(?) anyway due to an even more puzzling glitch that seemed to cause CPU to max out at 100% if the system tried to turn off graphics monitors internally.

Should you want me to file the report nevertheless, you can set up an account for my E-mail address at imreeil42@gmail.com, and I’d be able to provide info like CPU, driver versions, the NTP log file, OS network/IP settings, etc.

That KB sounds more believable than the dozen-year-old C runtime security update as a cause of issues. If it’s the Local Administrator Password Solution update that’s causing your trouble, perhaps the reason I’m not seeing it is I’m using Windows 11 Home, which appears to not be supported by LAPS. Are you using a professional or other edition of Windows 11?

I was able to create a bugs.ntp.org account for your email address. I emailed you the initial password. Please let me know if you are unhappy with the display name (taken from your profile here).

1 Like

I have at least attempted to submit it at https://bugs.ntp.org/show_bug.cgi?id=3812 now, to the best of my ability.

Are you using a professional or other edition of Windows 11?

I’m using Pro for Workstations.