Thank you. I thought something was wrong with my Windows setup or keyboard.

DSpellCheck hasn’t updated its manual since 2017.

At some point in the 8 years since then, they stopped assigning default keyboard shortcuts (probably because people complained that Alt+N interfered with the default windows hotkey for accessing the eNcoding menu).

However, Notepad++'s Settings > Shortcut Mapper allows you to go to the Plugin Commands tab, and Filter by DSpellCheck, then click on Find Next Misspelling, click Modify, and add your own preferred keyboard shortcut:

The problem is that with even a handful of plugins, if all plugins assigned default keyboard shortcuts for all their actions, or even their “most important” actions, you are essentially guaranteed to get a collision between those shortcuts. The better philosophy (that more of the best plugins are moving toward) is to not define any default shortcuts (or at least very few) to avoid collsions, and instead they now expect the user to define any shortcuts they want in Notepad++'s Shortcut Mapper interface, which is where all such things belong (IMO).

If you ever don’t like the shortcut a plugin gives you, or if it doesn’t give you one for a command you want a shortcut for, then use the Shortcut Mapper to change it to your liking.