ROS time synchronization in isolated local network

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Hi,

I suggest you use chrony for your setup.

Chrony can synchronise the system clock with NTP servers. [...] Typical accuracy between two machines synchronised over the Internet is within a few milliseconds; on a LAN, accuracy is typically in tens of microseconds. With hardware timestamping, or a hardware reference clock, sub-microsecond accuracy may be possible.

You can setup your "master" machine to be the NTP server, which can be used as a time source. Then the two slaves use your "master" device clock to synchronise their clocks. With this configuration you don't need internet, since the two salves use the master device as clock reference. You will have to play a bit with the configuration file of each machine, but it should be quite straightforward.

I work with a similar setup (3 PCs connected via switch) and the solution with chrony works very well.

Regards,

Marco.