diff --git a/start.sh b/start.sh
index 8db3d74..d5364ba 100644
--- a/start.sh
+++ b/start.sh
@@ -297,10 +297,18 @@ if [ "$SKIP_CONFIG_REBUILD" != "true" ]; then
   CURL_CMD+=("$URL")
 
   set +e
-  "${CURL_CMD[@]}"
+  CURL_ERR="$Temp_Dir/curl.err"
+  : > "$CURL_ERR"
+  "${CURL_CMD[@]}" 2>>"$CURL_ERR"
   ReturnStatus=$?
   set -e
 
+  echo "[DBG] curl rc=$ReturnStatus"
+  if [ -s "$CURL_ERR" ]; then
+    echo "[DBG] curl stderr (last 50 lines):"
+    tail -n 50 "$CURL_ERR"
+  fi
+
   if [ "$ReturnStatus" -ne 0 ]; then
     WGET_CMD=(wget -q -O "$Temp_Dir/clash.yaml")
     if [ "$ALLOW_INSECURE_TLS" = "true" ]; then