diff --git a/libraries/ArduinoOTA/ArduinoOTA.cpp b/libraries/ArduinoOTA/ArduinoOTA.cpp
index 24be99d374..3fe03300f1 100644
--- a/libraries/ArduinoOTA/ArduinoOTA.cpp
+++ b/libraries/ArduinoOTA/ArduinoOTA.cpp
@@ -318,6 +318,7 @@ void ArduinoOTAClass::_runUpdate() {
 
   if (Update.end()) {
     client.print("OK");
+    client.flush();
     client.stop();
     delay(10);
 #ifdef OTA_DEBUG
diff --git a/tools/sdk/lwip2/builder b/tools/sdk/lwip2/builder
index 163bb82dd9..5965154f1e 160000
--- a/tools/sdk/lwip2/builder
+++ b/tools/sdk/lwip2/builder
@@ -1 +1 @@
-Subproject commit 163bb82dd97e985df76c07d1c3f7325212cbdd5e
+Subproject commit 5965154f1ef522e223cb894e483f5e2c6684a321