Usually you cant roll back after certain security patch has been downloaded .
Flashing a firmware will only correct if firmware was corrupt, So your flashing the stock firmware . Me personally I think you have a issue with carrier or its sim possible, it should not auto populate that many APN . If you have another phone or can try that sim in another phone like family members see if it work properly there.
OK, here's the latest update. This past weekend, my other phone (the one on TW service) started working again on the old provider (literally out of the blue, no noticeable changes on my part).
As a result, I swapped the sims of the two phones. Just to recap here.
Phone 1 (all info in this post is about this one other than mentions of the other one)/SM-950U1/dialup speeds on TW, switched to Visible and can't connect to network
Phone 2/SM-950U/now working on TW.
Shut both phones down, swapped sim cards, rebooted
They both did the "new sim detected" dance and rebooted again.
Phone 2 (now with Visible sim) immediately starts working and a flood of texts come in from the time I was offline with my phone.
Phone 1 (now using the TW sim) still cannot connect to network. I went into the APN settings again and the TW one was there but was unchecked. I selected it but it didn't seem to make a difference. I forgot to check the Visible APN settings on phone 2 while it was working.
Shut down both phones again and swapped back and it went back to the previous status (Phone 1 not working with visible SIM).
So it seems on the surface that Visible's support is correct that the sim and their service is fine. However, one thing I noticed is that Visible's support mentioned today (I just like chatting with them) that they ONLY work with Verizon's 4G towers. Perhaps the large list of APNs that gets populated with the Visible SIM in my phone because the 4G antennae is malfunctioning so it can't select the correct APN? I suppose that could explain why it is giving the appearance of the provisioning/SIM isn't working? I don't really know if this makes sense but it does in my head. Happy to be set straight?
And the final question here is...if my guess above is correct (4G antennae not working), what are the odds that it's a firmware problem rather than a hardware problem? Any chance that re-flashing the current stock Firmware (or any other custom firmware for that matter) will fix it?