LAN stack gives out its LAN address: dev-lan sets FRONTEND_HOST to the published port on the host's default-route address, so the Panels dialog links a screen somewhere it can reach instead of app.localhost

docker/compose.lan.yml

@@ -7,6 +7,13 @@
 # whole app.
 services:
 
+  backend:
+    environment:
+      # The address the instance gives out: the link the Panels dialog shows a
+      # screen and the one its emails carry. app.${DOMAIN} resolves on this host
+      # only, so `make dev-lan` passes the published port on the LAN address.
+      - FRONTEND_HOST=${LAN_URL:-http://app.${DOMAIN:-localhost}}
+
   frontend:
     ports: !override
       - "${APP_PORT:-8080}:80"