BUG? Sophos Switch DoS Prevention blocks time synchronization of devices.

I'm editing my post here.

I have a Sophos CS110-24 switch

I noticed that no devices on my LAN could contact any NTP server to synchronize their time. I found out that it was the DoS prevention setting.

When enabled, no devices can synchronize to any NTP.

Immediately after disable the DoS protection, all devices can receive time updates. I have left DoS prevention off for now.

I have the latest firmware installed IMG-01.4.1466

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[edited by: Raphael Alganes at 10:14 AM (GMT -7) on 22 Apr 2024]
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  • No, the NTP are all public time servers. (ex.: time.windows.com, all public NIST time servers). The Sophos Firewall can contact time servers to update itself, but not any devices behind the switch.

    I have verified it was the issue after several tests. Disabling the DoS Prevention on sophos switch. then allows time synchronization.

    You can see from the screenshots, then time synchronization works with DoS disabled, then fails after turning DoS on.

    Screenshot 1: DoS Disabled

    Screenshot 2: DoS Enabled