NTP Client Stops syncing after upgrade to 6.40 from 6.38 on my RB1100AHx4
had to be sure so updated another device (RB751U-2hnd) same results, was working fine before.
on 751 after upgrade it showed synchronizing but after disable/enable it just shows started but never syncing.
used almost 20 different time servers, still same results.
here is my export : and the results:

Hi,
Any update on this? I have the same issue on ROS 6.43.12.
Thx in advance.

Does your router (the router itself, that's important) have connectivity with NTP servers? You can check it by running /tool traceroute 216.239.35.4 count=1. Do you have any firewall filter (or raw or ...) rules which might block UDP port 123 on chain=input or chain=output? Do you have fw rule similar to ?

Funny, I just figured out the problem, and you're absolutely right :

Does your router (the router itself, that's important) have connectivity with NTP servers?

was the issue. The router missed a route, and I was dumb enough to ping and trace NTP servers from my laptop and not from the router directly... Just added a routing policy on the router and it synchronized instantly.

BTW, part of the original problem was that this specific router is a NTP client (of Web NTP servers), and also a NTP server for other nodes in the private network. When the router was not synchronized, it sent NTP replies to the private nodes with an "unsynchronized" flag, so that the nodes ignored the packets. Thus the private nodes did not sync as well.

So as a note for myself, always check the whole NTP synchronization chain, because if a node does not synchonize, maybe that's because its server is not synchronized... and so on.