Scenario
========

* wlan0 is configured to connect to an internet-connected router and gets an IP via DHCP
* eth0 is set to a static IP (via */etc/dhcpcd.conf*, different net than wlan0) and connected to a net with no router, gateway or DHCP server.

Goal
====

I want to talk to devices connected to eth0 while maintaining internet connectivity through wlan0.

Problem
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As soon as a cable is connected, the internet connection goes away. The default route is always set to the non-existent gateway of eth0. Manually setting the default route to the gateway of wlan0 works, but I don't want to hardcode this, as wlan0 is connected to different networks with different IPs.