All I can tell you for sure is to check your kernal and os, try different combination until you get working realms and fort.
I don't setup server side stuff, and my partner doesn't use RZ. but we have working fort and realm names, and this is what he told me when I asked him how.
basically youll need a relative old linux os like say centos 4.8/4.9 or a redhat equivalent of that to get realm names working thats the only way i know of. wich ofcourse brings a few security risks with it you would have to deal with.
its the same for fort i think