Is there an update from version 3.0 (3.1) to version 4.0?

Does a patch (update) for Heroes III even exist in principle
from version 3.0 or 3.1 to version 4.0?

And one more question?
If such a patch doesn't exist, is it possible (and if so, how?)
for online players to connect if one has version 3.0 (3.1) and the other has 4.0?

As far as I know, no such patch exists... and there is no way to patch it.... because 4.0 is a complete collection..... while 3.1(3.0) is a separate "game"......
And regarding connecting—that's also impossible... the versions are different.. and they have different changes.... because for example in 4.0 there are no spells that are specialized for the Hero.. (for example restoration) =))