Pihole not showing index.php blockpage

Expected Behaviour:

When i visit a gravity blocked page, display default blockpage

Actual Behaviour:

just getting site not found

i found that my router, using ddwrt, uses No DNS Rebind
In order to make the blocked page work, disable it.
But i still get onoy site not found

Are there more options in ddwrt that i need to dis-/enable?

With the update to v4.0 the default blocking behaviour has been changed to NULL as it works better with https. you can read more about the changes Here