use strict ;
use warnings ;

##</code><code>##

my $xml = XML::Twig->new()->parsefile('example.xml') ;
$xml-> ... ;
$xml -> get_xpath('//ipaddress',0) -> set_text("<IP HERE>") ;

##</code><code>##

my $uri="https://hostname:9060/ers/config/networkdevice/<ID HERE>";
my $req = HTTP::Request->new( ...
$req->content($xml->sprint) ; # Strange, why is there another $xml->sprint here?
$req->...

##</code><code>##

my $res = $ua->request( $req ) ;
# Check the outcome of the response
if ($res->is_success) {
   print $res->status_line, "\n";
} else {
   print $res->status_line, "\n";
}