Why are the font icons not showing up?

Question

css

Such situation. When installing WooCommerce and Jetpack plugins, their icons are not displayed either in the admin panel or on the front-end. Instead of them - empty squares. Icons are displayed only in IE 9-11.
Opera, Chrome, Mozila, Safari - display empty squares.
Site encoding - UTF-8 Web server: Nginx
Example css:

#adminmenu #toplevel_page_woocommerce .menu-icon-generic div.wp-menu-image:before {
  font-family: WooCommerce!important;
  content: "\e03d";
  font-size: 1.3em!important;
}

What could be the problem and how to fix it? There is an opinion that the problem is with the web server, since there was no such problem on another hosting