Docker Socket Proxy DNS lookup fails - what am I missing?

[bmadtiger]

Host OS: Fedora CoreOS 44.20260621.3.1 (uCore)
Docker: version 29.5.3, build 1.fc44

• compose.yml
• arcane-ds-proxy.network.json
• arcane.log

The above configuration (pretty much what the docs suggest) gives me the following error in the web GUI (also see attached docker log)

Environment summary unavailable.
failed to connect to Docker: failed to create Docker client:
failed to negotiate Docker API version:
[arcane.log](https://github.com/user-attachments/files/29954337/arcane.log)
[arcane-ds-proxy.network.json](https://github.com/user-attachments/files/29954338/arcane-ds-proxy.network.json)

failed to connect to the docker API at tcp://arcane-ds-proxy:2375:
lookup arcane-ds-proxy on [::1]:53:
read udp [::1]:52222->[::1]:53:
read: connection refused

I've tried trouble-shooting with Claude (free) using both Haiku 4.5 and Sonnet 5 and the best either can give me is to fix the IP address of the proxy - which works - but raises the question of why the DNS lookup fails. Very occasionally it does actually work if IPv6 is enabled on the arcane-ds-proxy network, but then it fails the next time the container is started.

What am I doing wrong? Why doesn't the hostname work all the time?