fix(iot-client): point the UEAZ ATOP fallback at a host that exists

AGENTS.md

@@ -192,8 +192,9 @@ ordinary changes.
   switches end in `default:`, so `-Wswitch` never fires and a miss succeeds at the HTTP layer
   against a real, wrong data center; `dns_test.c` asserts only the PROD arm. Measured facts no
   file in the repo records (probed 2026-08-14): `SG` is absent from the PRE arm because it does
-  not exist in pre; `IOT_UEAZ_HOST` (`a1-ueaz.tuyaeu.com`) is **NXDOMAIN** — UE lives under
-  `tuyaus.com`, so the UE ATOP fallback path is dead; and on prod West-Europe's `httpsUrl` *flaps*
+  not exist in pre; `IOT_UEAZ_HOST` shipped as `a1-ueaz.tuyaeu.com`, which is **NXDOMAIN** — UE
+  lives under `tuyaus.com`, so the UE ATOP fallback was dead until it was repointed at
+  `a1-ueaz.tuyaus.com` (2026-08-31); and on prod West-Europe's `httpsUrl` *flaps*
   rather than being absent, so the device alternates between the DNS answer and the compile-time
   fallback across reboots.
 - **`OPRT_OK` from `atop_base_request()` means `success == true`, nothing more.**

CHANGELOG.md

@@ -5,6 +5,13 @@ All notable changes to this project are documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## [Unreleased]
+
+### Fixed
+
+- iot-client — US-East (`UEAZ`) fell back to an ATOP host that does not resolve(#32).
+  `IOT_UEAZ_HOST` is now `a1-ueaz.tuyaus.com`.
+
 ## [0.4.0] - 2026-08-27
 
 ### Added

modules/iot-client/src/iot_config_defaults.h

@@ -25,7 +25,7 @@
 #define IOT_CN_PRE_HOST "a1-cn.wgine.com"
 #define IOT_AZ_HOST "a1.tuyaus.com"
 #define IOT_AZ_PRE_HOST "a1-us.wgine.com"
-#define IOT_UEAZ_HOST "a1-ueaz.tuyaeu.com"
+#define IOT_UEAZ_HOST "a1-ueaz.tuyaus.com"
 #define IOT_UEAZ_PRE_HOST "a1-ueaz.wgine.com"
 #define IOT_EU_HOST "a1.tuyaeu.com"
 #define IOT_EU_PRE_HOST "a1-eu.wgine.com"