There are various versions and builds of 4D.
In general, it is always recomended that the client and server's version and build are the same.

It has been seen that in some cases clients can connect to non-matching servers. This may be possible if the main version is the same, but is still not recommended as this is not a supported, tested, or suggested strategy. This is due to potential issues from differences in the client compared to the server, this can cause the communication between the two to not be on the same wavelength and cause unforseen issues.

In more recent versions, 4D will generate a non-matching error when trying to connect versions of 4D that are not close enough. The Application version command can be used to compare the versions and build numbers.