I've been following the issue CM4 is missing IEEE1588-2008 support through BCM54210PE since I heard about IEEE1588-2008 support on the Compute Module 4 last year.
Apparently the little NIC included on every Compute Module 4—the BCM54210PE, which is different than the NIC on the Pi 4 model B (a BCM54213PE)—includes support for a feature called PTP, or Precision Time Protocol.
Nowadays, most people assume that all modern computers and operating systems have network time synchronization set up properly and switched on by default. However, this is not the case with many Linux servers—especially if you didn't install Linux and configure it yourself (as would be the case with most cloud-based OS images like those used to generate new servers on Linode).
After setting up a new server on Linode or some other Linux VPS or dedicated server provider, you should always do the following to make sure the server's timezone and date and time synchronization are configured and working correctly: