Ubuntu 18.04与20.04中systemd-timesyncd时钟同步状态显示差异及同步问题排查求助

各位好，我最近在给Ubuntu 18.04和20.04配置本地时间服务器同步时，遇到了一个困惑的问题，想请教下大家：

我给两个系统都配置了指向本地时间服务器的同步设置，但两者的状态显示却不一样：

• 在Ubuntu 18.04上，配置完成后查看状态，明确显示已经同步到时间服务器，状态正常；
• 但在Ubuntu 20.04上，状态一直停留在“Initial time synchronization to time server...”，始终没有切换到已同步的状态。

以下是两个系统的systemctl status systemd-timesyncd输出：

Ubuntu 20.04的状态输出 #

$ systemctl status systemd-timesyncd

● systemd-timesyncd.service - Network Time Synchronization
     Loaded: loaded (/lib/systemd/system/systemd-timesyncd.service; enabled; vendor preset: enabled)
     Active: active (running) since Sat 2023-03-18 23:17:29 IST; 2s ago
       Docs: man:systemd-timesyncd.service(8)
   Main PID: 476708 (systemd-timesyn)
     Status: "Initial synchronization to time server <server_ip>."
      Tasks: 2 (limit: 19009)
     Memory: 1.2M
     CGroup: /system.slice/systemd-timesyncd.service
             └─476708 /lib/systemd/systemd-timesyncd

.. systemd[1]: Starting Network Time Synchronization...
.. systemd[1]: Started Network Time Synchronization.
.. systemd-timesyncd[476708]: Initial synchronization to time server

Ubuntu 18.04的状态输出 #

$ systemctl status systemd-timesyncd

● systemd-timesyncd.service - Network Time Synchronization
     Loaded: loaded (/lib/systemd/system/systemd-timesyncd.service; enabled; vendor preset: enabled)
     Active: active (running) since Sat 2023-03-18 22:26:32 IST; 25min ago
       Docs: man:systemd-timesyncd.service(8)
   Main PID: 7607 (systemd-timesyn)
     Status: " Synchronized to time server <server_ip>."
      Tasks: 2 (limit: 4915)
     CGroup: /system.slice/systemd-timesyncd.service
             └─7607 /lib/systemd/systemd-timesyncd

.. systemd[1]: Starting Network Time Synchronization...
.. systemd[1]: Started Network Time Synchronization.
.. systemd-timesyncd[7607]: Synchronized to time server

我想知道：为什么Ubuntu 20.04一直显示初始同步状态，不会切换到已同步？如果它确实没有完成同步的话，该怎么解决这个问题呢？

备注：内容来源于stack exchange，提问作者Prof Monika Shah