I didn't look through the thread to see if this has been posted, but of late I've been having issues accessing SDN from Tapatalk. For whatever reason I'm able to get notifications (e.g., my posts being quoted, likes, PMs, etc.) but I always get a timeout error when I try to login or if I tap the notification. I haven't tried the SDN app because I'm not too into paying $1 or whatever it is for an app that likely won't work either since it just seems to be a skinned version of Tapatalk.
People mentioned not being able to view the site when the changes were first rolled out but I haven't had any issues until a few days ago.