I have a 12E that makes much trouble with restarts. Even with great Power 2A and that recommend resistore and capaticator rubbish.
After remove the shield it work some better and after remove that SMD Part the 12E works stabile without reboots... but also no WLAN lol
What does that SMD Part with the red cross?
I have order 7 x 12E and 1 x 12F. Most are Buggy... fast reboots only with simple code like
unsign double blabla = 0;
blabla = blabla + 1;
serial print (blabla);
Only 3 work stabile, the other break most time between 250 - 40000.