From dda901780c54a162d0c821f6ff442df6ed303b3e Mon Sep 17 00:00:00 2001
From: Theo Arends <11044339+arendst@users.noreply.github.com>
Date: Tue, 30 Dec 2025 17:09:54 +0100
Subject: [PATCH] Fix ESP8266 KNX unwanted reply (#24267)

---
 CHANGELOG.md                                    | 1 +
 RELEASENOTES.md                                 | 1 +
 lib/lib_div/esp-knx-ip-0.5.2/src/esp-knx-ip.cpp | 4 ++++
 3 files changed, 6 insertions(+)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index e6cd6db65..ac19ded23 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -18,6 +18,7 @@ All notable changes to this project will be documented in this file.
 - ESP32 BLE not starting (#24240)
 - GDK101 power on detection (#24242)
 - Udisplay backlight with SPI displays (#24277)
+- ESP8266 KNX unwanted reply (#24267)
 
 ### Removed
 
diff --git a/RELEASENOTES.md b/RELEASENOTES.md
index 522b796ed..a39c63cbe 100644
--- a/RELEASENOTES.md
+++ b/RELEASENOTES.md
@@ -127,6 +127,7 @@ The latter links can be used for OTA upgrades too like ``OtaUrl https://ota.tasm
 
 ### Fixed
 - ESP8266 TasmotaSerial flush receive buffer on executing `TasmotaSerial.flush();`
+- ESP8266 KNX unwanted reply [#24267](https://github.com/arendst/Tasmota/issues/24267)
 - ESP32-P4 unique MQTT Client based on hosted MCU MAC address
 - GDK101 power on detection [#24242](https://github.com/arendst/Tasmota/issues/24242)
 - Udisplay backlight with SPI displays [#24277](https://github.com/arendst/Tasmota/issues/24277)
diff --git a/lib/lib_div/esp-knx-ip-0.5.2/src/esp-knx-ip.cpp b/lib/lib_div/esp-knx-ip-0.5.2/src/esp-knx-ip.cpp
index 77abc7428..39fdf2dcc 100644
--- a/lib/lib_div/esp-knx-ip-0.5.2/src/esp-knx-ip.cpp
+++ b/lib/lib_div/esp-knx-ip-0.5.2/src/esp-knx-ip.cpp
@@ -558,7 +558,11 @@ void ESPKNXIP::__loop_knx()
 
   DEBUG_PRINTLN(F(""));
 
+#ifdef ESP8266
+  while (udp.available()) { udp.read(); }  // ESP8266 does endPacket() on flush() which in turn does send() which is NOT what we want
+#else
   udp.flush();
+#endif
 
   knx_ip_pkt_t *knx_pkt = (knx_ip_pkt_t *)buf;