XF 2 Login/logout/register from external php site


Currently, I have a website that I connected with XenForo.
Now the forum was always on XenForo 1.5.*
With my own site I was able to register users and add them to XenForo.
Also, login on my site logged in the user in XenForo.
Logout on my site did log out the user from XenForo as well.
And when a user changed their password it was changed in XenForo as well.

However, now with XenForo 2.2.4 it is not working anymore.
I have done some investigation, but I cannot get it working :(

Can anyone help me with this? I'm willing to pay for this of course.
And I can also share the code that was working previously.