two wifi networks on raspberry pi zero w

Question

This is a very specific use case: I need the RPi zero w to generate a local Wifi network that my client will connect to from a smart phone, browse to a specific IP address and setup the second wifi connection through a web form (ssid & psk).

The idea is that my final product has no screen, and it needs to be configured by the user to reach its wifi network.

For now, I'm able to create a local wifi network (I only tried on B+), and use the ethernet port to reach the internet, but I will not have ethernet on my final product.

My question is: is that possible? and if so, how?

I'm open to other ideas to reach the same goal (why not Bluetooth...)

Answer 1

Yes, it's possible.

Look for the recipes wlan to eth with NAT, then replace eth0 with your wlan1. One excellent is, albeit in German, this one which walks you through all the gory details: https://www.elektronik-kompendium.de/sites/raspberry-pi/2002171.htm

While I'm writing this on my desk is sitting a Zero W with it's internal wlan0 acting as AP. Connected to it is a tablet. I've an USB WLAN dongle attached via an USB OTG shim, it connects to my home network with Internet access. I only need it to update the Pi. But it is possible to NAT between the upstream additional wlan1 and the AP wlan0. Bridging is not possible, but routing is. I've done this all also on a Pi 3B beginning of this year. The NAT rules even work when the wlan1 upstream IP is dynamic. I was working from the description I linked to above.