A cleaned up copy of what you posted:

#!/usr/bin/perl

use strict;
use warnings;

my @cmd = ('/sbin/route');
push @cmd, 'add'; 
push @cmd, 'default'; 
push @cmd, 'gw',
push @cmd, '172.16.0.200', 
push @cmd, 'dev'; 
push @cmd, 'enxb827eb95400d'; 
system(@cmd);
[download]

some lines end with commas when they should be semicolons:

#!/usr/bin/perl

use strict;
use warnings;

my @cmd = ('/sbin/route'); 
push @cmd, 'add'; 
push @cmd, 'default'; 
push @cmd, 'gw'; 
push @cmd, '172.16.0.200'; 
push @cmd, 'dev'; 
push @cmd, 'enxb827eb95400d'; 
system(@cmd);
[download]

If in doubt, print what your variables contain. Tutorials->PerlMonks for the Absolute Beginner/Basic debugging checklist.