Use host-published Datum admin port

docker-compose.yml

@@ -1,7 +1,7 @@
 # gashboard — deploy as a Portainer Stack on the same Umbrel host that runs Datum.
 #
-# Joins Umbrel's shared Docker network so the API can reach Datum through
-# Docker DNS instead of a changing container IP.
+# Uses host networking so the API can reach Datum through the port Umbrel
+# already publishes on the host, avoiding container DNS and changing IPs.
 
 services:
   gashboard:
@@ -21,9 +21,8 @@ services:
       PORT: "1337"
       LOG_LEVEL: "${LOG_LEVEL:-info}"
       CORS_ORIGIN: "${CORS_ORIGIN:-}"
-      # Datum's service alias on Umbrel's shared app network. Override this if
-      # your Umbrel install exposes a different DNS name.
-      DATUM_URL: "${DATUM_URL:-http://datum:21000}"
+      # Datum's admin UI/API is published by Umbrel on the host at port 21000.
+      DATUM_URL: "${DATUM_URL:-http://127.0.0.1:21000}"
       DATUM_ADMIN_USER: "${DATUM_ADMIN_USER:-admin}"
       DATUM_ADMIN_PASSWORD: "${DATUM_ADMIN_PASSWORD?must be set}"
       DATUM_POLL_INTERVAL_MS: "${DATUM_POLL_INTERVAL_MS:-5000}"
@@ -31,17 +30,10 @@ services:
       NOSTR_ALLOWED_NPUBS: "${NOSTR_ALLOWED_NPUBS?must be set}"
       JWT_SECRET: "${JWT_SECRET?must be set}"
       JWT_TTL_SECONDS: "${JWT_TTL_SECONDS:-86400}"
-    ports:
-      - "${PORT:-1337}:1337"
-    networks:
-      - umbrel_main_network
+    network_mode: host
     healthcheck:
       test: ["CMD", "wget", "-qO-", "http://127.0.0.1:1337/healthz"]
       interval: 30s
       timeout: 5s
       retries: 3
       start_period: 15s
-
-networks:
-  umbrel_main_network:
-    external: true