diff --git a/lib/common.sh b/lib/common.sh
index 1e0bc2f..c4f9bd1 100644
--- a/lib/common.sh
+++ b/lib/common.sh
@@ -70,8 +70,10 @@ _project_root() {
 }
 
 # Source .env and export all variables.
-# Uses set -a/+a to auto-export every variable defined in the file,
-# making them available to child processes (envsubst, ssh, etc.).
+# Internal API URLs are auto-derived from container IPs:
+#   GITEA_INTERNAL_URL        = http://UNRAID_GITEA_IP:3000
+#   GITEA_BACKUP_INTERNAL_URL = http://FEDORA_GITEA_IP:3000
+# so users do not need to set these URL vars manually in .env.
 load_env() {
   local env_file
   env_file="$(_project_root)/.env"
@@ -105,6 +107,15 @@ load_env() {
     value="${value%"${value##*[! ]}"}"
     export "$key=$value"
   done < "$env_file"
+
+  # Derive internal API URLs from dedicated container IPs.
+  # This keeps one source of truth: *_GITEA_IP.
+  if [[ -n "${UNRAID_GITEA_IP:-}" ]]; then
+    export GITEA_INTERNAL_URL="http://${UNRAID_GITEA_IP}:3000"
+  fi
+  if [[ -n "${FEDORA_GITEA_IP:-}" ]]; then
+    export GITEA_BACKUP_INTERNAL_URL="http://${FEDORA_GITEA_IP}:3000"
+  fi
 }
 
 save_env_var() {
@@ -220,8 +231,8 @@ _ENV_VAR_NAMES=(
   FEDORA_MACVLAN_IP_RANGE FEDORA_GITEA_IP
   GITEA_ADMIN_USER GITEA_ADMIN_PASSWORD GITEA_ADMIN_EMAIL
   GITEA_ORG_NAME GITEA_INSTANCE_NAME GITEA_DB_TYPE GITEA_VERSION ACT_RUNNER_VERSION
-  GITEA_DOMAIN GITEA_INTERNAL_URL
-  GITEA_BACKUP_INTERNAL_URL GITEA_BACKUP_MIRROR_INTERVAL
+  GITEA_DOMAIN
+  GITEA_BACKUP_MIRROR_INTERVAL
   BACKUP_STORAGE_PATH BACKUP_RETENTION_COUNT
   RUNNER_DEFAULT_IMAGE
   GITHUB_USERNAME GITHUB_TOKEN
@@ -243,8 +254,8 @@ _ENV_VAR_TYPES=(
   nonempty ip
   nonempty password email
   nonempty nonempty db_type nonempty nonempty
-  nonempty url
-  url nonempty
+  nonempty
+  nonempty
   path integer
   nonempty
   nonempty nonempty