Traefik
Traefik (pronounced traffic) is a modern HTTP reverse proxy and load balancer that makes deploying microservices easy.
Configuration
Section titled “Configuration”DNS resolution (split-horizon DNS)
Section titled “DNS resolution (split-horizon DNS)”Traefik determines the backend address for a host-network application (one that runs with network_mode: host, such as Home Assistant, Netdata, or Plex) by resolving your host’s FQDN. By default the Traefik container resolves names using 8.8.8.8.
If you use split-horizon DNS — where your host name resolves to a public IP externally but a private LAN IP internally — the default 8.8.8.8 returns the public IP. Traefik then routes host-network backends to that public IP, which fails for any service whose port is not forwarded, returning 502 Bad Gateway (for example, Home Assistant on port 8123).
To fix this, point Traefik at your LAN resolver so those backends resolve to the internal LAN address:
traefik_dns_servers: ["192.168.1.1"] # your LAN DNS resolver