Richard Venancio

This plugin used to get de sub menu refers the current item menu, and show this with a menu, for exemple a sub menu left.
Supose you have a big main menu, and this have a lot submenus, so, to show yours submenus in a side of your site, you create one new menu in wordpress for each submenu you have, and create codes to define which submenu you show, according the location in hierarchy’s menu you are.
This is very tiring and biggest, for just show the submenu, then this plugin do all things for you, but don’t create any menu, it just get the submenu according the main menu.

RVSubMenu

This plugin used to get de sub menu refers the current item menu, and show this with a menu, for exemple a sub menu left.

Gecka

PHP 5 required. Please be sure to check your PHP version before marking the plugin as broken.
Submenu enhances the WordPress 3.x navigation system. When you have a website based on WordPress with a lot of pages, but you need a custom menu, it can be tedious to have to add a menu entry for each page created. Submenu just does it automatically.
Submenu also allows you to put menus or portion of menus anywhere in your site: sidebar, templates or page contents.
Languages available: english, french
Contribute: <a href="https://github.com/Gecka-Apps/Wordpress_Gecka_Submenu" rel="nofollow ugc">This plugin is on GitHub</a> !
<a href="http://gecka-apps.com/wordpress-plugins/gecka-submenu-pro/" title="Discover the pro version" rel="nofollow ugc">Discover the pro version</a> by checking out the <a href="http://www.youtube.com/watch?v=DHjMfD-k2Mo" rel="nofollow ugc">Gecka Submenu Pro video</a>:
<iframe loading="lazy" class="youtube-player" width="750" height="422" src="https://www.youtube.com/embed/DHjMfD-k2Mo?version=3&rel=1&showsearch=0&showinfo=1&iv_load_policy=1&fs=1&hl=en-US&autohide=2&wmode=transparent" allowfullscreen="true" style="border:0;" sandbox="allow-scripts allow-same-origin allow-popups allow-presentation allow-popups-to-escape-sandbox"></iframe>

Gecka Submenu

Works fine for me

Submenu autopopulates any nav menu page item with its children and allows to put menus, or portion of menus, anywhere in your site.

RVSubMenu vs Gecka Submenu