diff --git a/src/network/HttpDownloader.cpp b/src/network/HttpDownloader.cpp
index 9179d5a4..44a5a543 100644
--- a/src/network/HttpDownloader.cpp
+++ b/src/network/HttpDownloader.cpp
@@ -58,7 +58,10 @@ HttpDownloader::DownloadError runGetWolf(const std::string& startUrl, const std:
       LOG_ERR("HTTP", "wolfSSL bad URL: %s", url.c_str());
       return HttpDownloader::HTTP_ERROR;
     }
-    http.addHeader("User-Agent", "CrossPoint-ESP32-" CROSSPOINT_VERSION);
+    // setUserAgent replaces SecureHttpClient's built-in UA; addHeader would
+    // append a second User-Agent header, which strict servers reject (aiohttp
+    // answers 400 "Duplicate 'User-Agent' header found").
+    http.setUserAgent("CrossPoint-ESP32-" CROSSPOINT_VERSION);
     if (!username.empty() && !password.empty()) {
       const std::string credentials = username + ":" + password;
       const String encoded = base64::encode(credentials.c_str());