Can't connect to server, same wifi, same version?

I am on samsung note 4 and my sister on samsung note 2. Originally i could connect to her server and hers to mine. but then it stopped working a few times and now i can see her server and she can see mine but when you try to connect it just stops on the 'generating world' screen then crashes. Ive restarted phones, wifi but havent uninstalled app as wasnt sure if it deleted world's? tried taking a screenshot but that screen is frozen then disconnects you.