Fix ESP8266 TasmotaSerial flush receive buffer on executing TasmotaSerial.flush();

CHANGELOG.md

@@ -14,6 +14,7 @@ All notable changes to this project will be documented in this file.
 ### Fixed
 - DALI watchdog exception
 - TuyaMCU v1 exception 28 regression from v15.1.0.1 reverted PR24063 (#24220)
+- ESP8266 TasmotaSerial flush receive buffer on executing `TasmotaSerial.flush();`
 
 ### Removed
 

RELEASENOTES.md

@@ -119,5 +119,6 @@ The latter links can be used for OTA upgrades too like ``OtaUrl https://ota.tasm
 - Vid6608 library from v1.0.2 to v1.0.3 [#24218](https://github.com/arendst/Tasmota/issues/24218)
 
 ### Fixed
+- ESP8266 TasmotaSerial flush receive buffer on executing `TasmotaSerial.flush();`
 - DALI watchdog exception
 - TuyaMCU v1 exception 28 regression from v15.1.0.1 reverted PR24063 [#24220](https://github.com/arendst/Tasmota/issues/24220)

lib/default/TasmotaSerial-3.7.0/src/TasmotaSerial.cpp

@@ -353,14 +353,15 @@ bool TasmotaSerial::overflow(void) {
 void TasmotaSerial::flush(void) {
   if (m_hardserial) {
 #ifdef ESP8266
-    Serial.flush();
+    Serial.flush();    // Flushes Tx only
+    while (Serial.available()) { Serial.read(); }  // Flushes Rx
 #endif  // ESP8266
 #ifdef ESP32
     TSerial->flush();  // Flushes Tx only https://github.com/espressif/arduino-esp32/pull/4263
-    while (TSerial->available()) { TSerial->read(); }
+    while (TSerial->available()) { TSerial->read(); }  // Flushes Rx
 #endif  // ESP32
   } else {
-    m_in_pos = 0;
+    m_in_pos = 0;      // Flushes Rx, Tx is always flushed
     m_out_pos = 0;
   }
 }