I have a 128GB cellular model iPad mini 4 that I have as part of a Share Everything plan on Verizon (exclusively made up of tablets). For what it's worth, I ordered this iPad mini from Apple, and then swapped out the Apple SIM for the free Verizon SIM and then joined it to my plan thereafter. Suddenly, today, I started to get error messages that say "No SIM installed" and my upper left status bar says "No SIM" instead of "Verizon" with signal strength dots. It eventually reverts to "Verizon" (after presumably seeing my SIM card again) with the dots. I have rebooted the mini, but it still seems to happen. Before I go through the no-brainer next steps of "reset networking settings", "calling Verizon", "calling Apple", "doing a DFU restore" type troubleshooting tasks, I'm curious; does this sort of thing happen often with either iPhones or cellular model iPads? And if so, what sorts of problems are they usually indicative of?