use the non-greedy .+? modifier + the optional group (?: ... )*

my $test  = "Server list (Win2K/Win2003/XP) 6.26.5.1.5";
my $test1 = "Server list 6.26.5.1.5";

# $test =~ /(.*)(\(.+\))(.*)/;
my $regexp = qr{             # note: greedy (.+) vs. non-greedy (.+?) 
+qf.
                  (.+?)      # capture what comes but look ahead => $1
                  \s*        # optional whitespace
                  (?:          # start optional group (?: ... )?
                    \(         # opening bracket 
                    ([^)]+)    # get what's in the bracket => $2
                    \)         # closing bracket
                  )?           #  - optional
                  \s*        # possibly followed by some whitespace
                  ([\d.]+)   # then look for numbers and dots => $3
                  $          # which is anchored at the string end
               }x;
               
if( $test =~ /$regexp/ ) {  # if( $test1 =~ /$regexp/ ) 
   
   my ($prod_name, $platform, $version) = ($1, $2, $3);
   
   if(defined $platform) {
      print "$prod_name, $platform, $version"
   }
   else {
      print "$prod_name, <none>, $version"
   }
      
}
[download]

Regards

mwa