From 5048777e06025c41cbcdc4846e7aa41d7470de4e Mon Sep 17 00:00:00 2001
From: s-hadinger <49731213+s-hadinger@users.noreply.github.com>
Date: Sat, 17 Dec 2022 22:41:21 +0100
Subject: [PATCH] Fix IPV6 compilation on ESP8266 (#17429)

---
 tasmota/my_user_config.h                 | 5 ++---
 tasmota/tasmota_support/support_wifi.ino | 4 +++-
 2 files changed, 5 insertions(+), 4 deletions(-)

diff --git a/tasmota/my_user_config.h b/tasmota/my_user_config.h
index 0b879687f..6ca0fa850 100644
--- a/tasmota/my_user_config.h
+++ b/tasmota/my_user_config.h
@@ -407,9 +407,8 @@
 
 // -- IPv6 support -------------------------------
 // #define USE_IPV6                                 // Enable IPv6 support (if the underlying esp-idf is also configured to support it)
-                                                 // Code size increase:
-                                                 //   ESP8266: tbd
-                                                 //   ESP32: tbd
+                                                 // Code size increase: ESP8266: +34.5kb
+                                                 // Enabled by default on ESP32 and variants
 
 // -- ESP-NOW -------------------------------------
 //#define USE_TASMESH                              // Enable Tasmota Mesh using ESP-NOW (+11k code)
diff --git a/tasmota/tasmota_support/support_wifi.ino b/tasmota/tasmota_support/support_wifi.ino
index 4d8867573..d03b55699 100644
--- a/tasmota/tasmota_support/support_wifi.ino
+++ b/tasmota/tasmota_support/support_wifi.ino
@@ -922,7 +922,9 @@ bool WifiDNSGetIPv6Priority(void) {
 
   // any change of state requires a dns cache clear
   if (had_v6prio != v6prio) {
-    dns_clear_cache();
+#ifdef ESP32
+    dns_clear_cache();    // this function doesn't exist in LWIP used by ESP8266
+#endif
     had_v6prio = v6prio;
   }