I have just setup CATIA V5R21 ( for fun )
try to start Catia => no license server found !
R21 support now the new DSLS server , but by default do not recognize LUM server anymore ....
to ba able to use my LUM server , I have to add system variable
Variable Value: LEGACY
(I have found this information with Google , but I do not succeed to find it with V5R21 doc ! )