After installing https://www.dokuwiki.org/plugin:randompage2, appending ?do=randompage or ?do=nsrandompage to a page url will redirect to a random page within the wiki or within the namespace respectively.

For example, https://www.kamaraju.xyz/dk/start?do=randompage will redirect to a randompage in this wiki and https://www.kamaraju.xyz/dk/public/sotm/start?do=nsrandompage will redirect to a randompage within the public/sotm namespace.

Further, if you install the ShortcutKey Plugin (https://www.dokuwiki.org/plugin:shortcutkey) and map

Set “Shortcut key to show random page within current namespace (Randompage plugin is required)” to N
Set “Shortcut key to show random page (Randompage plugin is required)” to A

in the configuration settings (Admin → Configuration Settings → Plugin → Shortcutkey), you can use a and n to get a random page within the wiki and within the namespace respectively.

Ref:- https://github.com/solewniczak/dokuwiki-plugin-randompage2/issues/5