title: Access internet through 3G USB modem (ppp0) with wlan0 and eth0
body: <p>I have a Raspberry Pi 3 B+ and a Huawei 3G USB modem. I would like to be able to connect to the internet using the eth0 <em>and</em> wlan0 interface, but all I was able to achieve is to connect via one or the other interface, but not both.</p>
  
  <p>I have setup the configuration to dial into the cell provider, as well as all the steps needed to configure a static ip address and doing all the configuration with the NAT as described in this post: <a href="https://www.benfreke.org/201712/raspberry-pi-3g-4g-hotspot/" rel="nofollow noreferrer">https://www.benfreke.org/201712/raspberry-pi-3g-4g-hotspot/</a> (scroll to "CREATING A WIFI HOTSPOT"). However, this gives me access to access the internet through the Pi's wireless chip, but I have no way to access the internet through a wired connection using the ethernet (eth0). I would like to be able to do <em>both</em>, access through wlan0 but also when connecting an internet cable to the Pi. How can I achieve this? I can setup accessing the internet through the eth0 network, by simply replacing all the wlan0 configuration by eth0 in the tutorial, but then I don't have access to the wlan0 network. Is there a way to achieve both? Alternatively, I have a Apple's Airport Express wireless router, so if there is a way to configure the Pi so I can simply wire it to the Airport Express and then have the Express do the wireless, that would work too, but it does not seem to work when I follow the tutorial, and replace wlan0 by eth0. The code is all essentially the same as in the tutorial linked here.</p>