Why is node ordering different between two environments ?

I have noticed that the way the nodes are ordered is different between 2 different environments.

If I create the following global :

set ^TEMP("Z")=1
set ^TEMP("Ä")=1

Then I dump it with zwrite, I get this (which is expected):

^TEMP("Z")=1
^TEMP("Ä")=1

However, on another machine, it gives me this :

^TEMP("Ä")=1
^TEMP("Z")=1

The same goes for the following command (which return 0 or 1, depending environment) : 

write "Z"]]"Ä"

Both are running Windows 10, but one is running IRIS 2021.1, the other CACHE 2017.2.2.

I don't think that's the reason, maybe there's something else (a configuration in Portal). Has anyone encountered a similar problem and knows what is wrong?

I also tested the following JS code: 

alert("Z"<"Ä");

It displays "1" in both environments (so AFAIK this is a CACHE issue, not an operating system issue).