Manual:$wgMainPageIsDomainRoot

Server URLs and file paths: $wgMainPageIsDomainRoot
Controls if the main page should be served as the domain root.
Introduced in version:1.34.0 (Gerrit change 520139; git #a5deeac5)
Removed in version:Still in use
Allowed values:(boolean)
Default value:false

If true, users visiting your wiki's main page from the domain root will not be redirected. This setting requires that short URLs be configured in order to be functional.