This works on desktop Firefox, but doesn't work on Firefox on Android. I suspect that this is because of DNS over HTTPS.
What I tried:
I installed Firefox Beta on Android, went to about:config and set
5 as described here. Then, I removed all DNS cache present in Firefox on Android itself.
Then, I 'hard reloaded' http://koffiezetapparaat.lan by long pressing the reload button.
I still get a 404.
Network traffic analysis with
tcpdump on my OpenWrt router showed no port 53 traffic, but a lot of port 443 traffic.
Please bear in mind that navigating to http://koffiezetapparaat on Chrome on Android works as it should, it resolves to http://192.168.1.120.
I supect that Firefox on Android still uses DNS over HTTPS and want to know a definitive way of disabling that.