I was working through the Raspberry Pi Cellular Gateway Tutorial and I was striking an odd issue. I was able to solve the issue, so I just thought I would share my findings in case anyone else runs into the same issue - I would also welcome any comments.
I am using a Raspberry Pi Zero with Raspbian Stretch Lite, November 2017.
On the initial setup, the NodeMCU was able to connect to the friendly-raspberry Access Point and the messages were sent fine. However, after a reboot of the Raspberry Pi Zero, although I could connect to the friendly-raspberry from the Lap Top, the Node MCU could not make a connection. The SSID could be found - just no connection.
Only after re-issuing the following commands, would the NodeMCU suddenly be able to make a connection
sudo service hostapd start
sudo service isc-dhcp-server start
I went over the steps a couple of times and could not fault what I had done. Reading though this entry on the Raspberry Pi forum, I added the following line to the /etc/network/interfaces file, just above the allow-hotplug wlan0 line.
auto wlan0
After a reboot, the NodeMCU is able to connect without any further issue and start sending messages.
Although it is working, I am still a little unsure about this as a solution since the Adafruit guide for the same Access Point set up, explicitly says to comment out that line if it exists.