I was thinking that some app did that you provided the clue it was just that with the disconnect from WiFi.
Sorry but no it will not tell you what app so look back at what apps are not stock. That's why we factory reset and test for a time then load an app and wait.
I recently got a new straight talk phone , a Alcatel tcl .. and I have recieved several text messages from random 5 digit numbers prompting me to download software updates. They never have a description of what the update is, or any record on my phone of what the update did. Also , when contacting straight talk they have no record of me recieving these messages. Is it possible , I am receiving these messages from my router? I ask that because I know a certain person who works for my local internet company who is less than a stand up person.. I am wondering how can I tell the nature of these "updates" once I disconnected from my wifi I no longer recieved them ... I got 5 or 6 of these "updates" in the first week of having this phone. I am actually pretty concerned as to why this is happening and even more so once I realized they were not messages that are seen on my phone records with my provider.