I have found that I can get users working as desired in our porta/child portal implementation if I do the following:
1- create a link to windowssignin.aspx on the home page. when users click on this they are recognized by DNN.
2 - the AD module leaves a blank display name, making it impossible to tell if DNN recognized the user. I have created an insert trigger on dnn_Users that updates the display name.
3 - DNN does not make a user_portals record for any but the parent portal. When I add a record for the child portal of interest, they are able to get to the portal.
4 - DNN only makes user_Roles records for Subscribers and Registered Users. I have to manually add the user to the desired group in User_roles. This is occurring despite the fact that I have turned AD integration on and created a DNN user role with identical name (including case) to the AD group I wish to synch it to.
At this point, users are able to access the child portal, and only see the content we configure. This AD integration is critical for us as we are using it in our Customer Service group and have different modules on pages visible to our Sales vs. Tech users, with some modules visible to all. We can actually live with the blank display name, and missing user_portal record (fixing both with a trigger), but the user group synchronization is really critical, and would be a shame to have to maintain manually in parallel to our AD.
I will try copying windowssignin.aspx to the child portal folders and see if this resolves the need for the autologin link.
I am interested in providing whatever info or suggestions I can to help with this part of the project.