rage_pang141 I recently found out that on the secondary profiles it is not possible to change private DNS.
Network settings apply globally to all user profiles, and many of the settings can only be accessed from the owner profile. That's just how user profiles work on Android.
rage_pang141 Do you know if there is a way to be able to access a second profile after restarting the smartphone?
No, that's not possible, at least not currently. That's not something that GrapheneOS would change, so such a change would need to come from upstream.