At this moment, I have three systems in the pool. One system with IPv4 and IPv6 and two systems with IPv6 only. All systems are connected to the same router. The scores for the IPv6 servers are good: the overall score is a solid 20 and also nearly all individual scores are 20. Maybe once or twic…

Hi, what is your current bandwidth setting and how much did you decrease it? Also, after lowering the setting it takes time for the traffic flow to subside.

At this moment, the IPv4 server is at 2 Gbps and the IPv6 servers are at 3 Gbps. I tried as low as 100 Mbps. But even after several days, there is still some packet loss. I’ll try again and report back.

What country zone(s) are your servers in? Acknowledging that you did not yet indicate which server(s) we are talking about (i.e., likely you didn’t for a reason), in case that wasn’t on purpose, it would help if you could indicate which they are.

Sorry, these are my servers: https://www.ntppool.org/a/Maurice They are in NL, Europe and global zone.

My guess is on your router. For IPv4 I guess you are using port forwarding/DNAT to an private IP on your network? Then most likely the NAT table in your router overflows because your router tries to keep the connection state in memory. For NTP over UDP you can try to disable stateful forwarding be…

This was also my first guess (and I did hit the limits at first), but after increasing the maximum number of states and decreasing the time that a state is kept in memory I can see that the number of states is far below the limit. At this moment (with the lowered bandwidth setting) there are around…

I guess it might be bad ISP peering on the local path to the monitor. My server in the nl zone is keeping perfect score to all european monitors. In a quick test to your server I don’t see any packet loss.

Seeing that a few monitors have problems reaching your server and the other monitors give you a perfect 20 score, I find it unlikely that the problem would be in your server or your router. As mlichvar wrote above, it’s probably some sort of a routing/peering issue somewhere along the path. I would …

[image] Maurice: the monitors that are closest (both geographically and in terms of network latency), have the worst score The two monitors in the Netherlands have consecutive IP addresses, which might explain why both give bad scores for you, vs. a hypothetical, more diverse deployment withi…

Monitors and packet loss

Server operators

MagicNTP February 11, 2025, 5:31pm 10

Strictly speaking, NAT would not need to be stateful to effect port forwarding. But indeed, it depends on the implementation as to whether stateless port forwarding is available.

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Monitors and packet loss

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