I can't reproduce this behaviour with the latest XML::Twig. The XML looksproperly indented. Which version are you using? If it is a recent one (3.10+), could you please post a minimal test that I could run? Thanks

Just as a side note, you can write $ps->insert_new_elt( Server => { Name => "New_1"}); instead of $ps->insert_new_elt("Server")->set_att('Name', "New_1");.