I noticed an interesting problem with my Arduino Primo. If I power it from my laptop or an iPhone charger through the USB connector, it will execute my wifi code fine. However, if I use external power (I've tried from 3.5 to 4.7 volts), it does not establish a wifi connection.
I've looked at the schematic and I don't see a separate power circuit to the ESP8266. I thought at first it might be missing the serial connection but it worked fine with an iPhone charger. I searched the net to see if others have complained about the same thing, but the Primo doesn't have much of a following.
The literature says the external source should range between 4.75 and 5.25 volts. But the built-in charger doesn't kick in until the external source goes below 3.5v and most Lithium Ion batteries run at 3.7 volts so I figured I am in the right ballpark. I'll try using an external voltage of 5 v but would be surprised if that were the solution (no 5 v Lithium ion batteries).
Other than this, the Arduino Primo is great!
Just for the record, I hooked the external power connector to a 5 volt source (since the only documentation I've seen says it should be between 4.75 and 5.25 volts) and still everything but the wifi works fine. Truly bizarre!
Final comment: Got the wifi to work by supplying 5 volts (even worked down at 4.2 volts) by connecting it to the Vin pin. So, while I don't understand why it doesn't let wifi work with a battery through the external connector, I can use the Vin pin. This allows me to turn the power on and off with a switch instead of plugging it into a supply.