I'm trying to get a navigation in the events of event manager
the next/previous post links work but they are ordered by creation date instead of event date.
How could it be possible to change this?
The function WordPress ultimately uses for this is get_adjacent_post(), which has filters that allow you to modify the query directly. You'd have to modify the
ORDER BY clauses to join the post meta table and order by your custom field.
Another option is the Ambrosite Next/Previous Post Link Plus plugin.