Without reading your code too close, I think it is because your decon_server subroutine gets called too early:

my %options = (
...
  "decon"          => \&decon_server, 
); 
...
    die_usage()
       if (!GetOptions(%options));
[download]

decon_server will get called from within GetOptions(), which is too early since none of the connection setup has happened yet.

I would suggest that the approach of setting a flag, as used in the other options, is likely better:

my %options = (
...
  "decon"          => \my $do_decon_server, 
); 
...
    die_usage()
       if (!GetOptions(%options)); 
...
    if( $do_decon_server ) {
        decon_server();
    };
[download]