diff --git a/examples/aws/awsiot.c b/examples/aws/awsiot.c
index cd77c3807..09c3a05ad 100644
--- a/examples/aws/awsiot.c
+++ b/examples/aws/awsiot.c
@@ -60,7 +60,9 @@ static int mTestDone = 0;
 #define APP_HARDWARE         "wolf_aws_iot_demo"
 #define APP_FIRMWARE_VERSION LIBWOLFMQTT_VERSION_STRING
 
+#ifndef MAX_BUFFER_SIZE
 #define MAX_BUFFER_SIZE         512    /* Maximum size for network read/write callbacks */
+#endif
 #define AWSIOT_HOST             "a2dujmi05ideo2-ats.iot.us-west-2.amazonaws.com"
 #define AWSIOT_DEVICE_ID        "demoDevice"
 #define AWSIOT_QOS              MQTT_QOS_1
diff --git a/examples/azure/azureiothub.c b/examples/azure/azureiothub.c
index 463e67256..dc8205b65 100644
--- a/examples/azure/azureiothub.c
+++ b/examples/azure/azureiothub.c
@@ -76,7 +76,9 @@ static int mTestDone = 0;
  * https://azure.microsoft.com/en-us/documentation/articles/iot-hub-sas-tokens/#using-sas-tokens-as-a-device
  * https://docs.microsoft.com/en-us/azure/iot-hub/iot-hub-mqtt-support
  */
+#ifndef MAX_BUFFER_SIZE
 #define MAX_BUFFER_SIZE         1024    /* Maximum size for network read/write callbacks */
+#endif
 #define AZURE_API_VERSION       "?api-version=2018-06-30"
 #define AZURE_HOST              "wolfMQTT.azure-devices.net"
 #define AZURE_DEVICE_ID         "demoDevice"
diff --git a/examples/firmware/fwclient.c b/examples/firmware/fwclient.c
index 351eaf4b4..22259fd8d 100644
--- a/examples/firmware/fwclient.c
+++ b/examples/firmware/fwclient.c
@@ -55,7 +55,9 @@
 #include "examples/mqttnet.h"
 
 /* Configuration */
+#ifndef MAX_BUFFER_SIZE
 #define MAX_BUFFER_SIZE         FIRMWARE_MAX_PACKET
+#endif
 
 /* Locals */
 static int mStopRead = 0;
diff --git a/examples/firmware/fwpush.c b/examples/firmware/fwpush.c
index 7b2ee2ad6..676ee95e7 100644
--- a/examples/firmware/fwpush.c
+++ b/examples/firmware/fwpush.c
@@ -56,7 +56,9 @@
 #include "examples/mqttnet.h"
 
 /* Configuration */
+#ifndef MAX_BUFFER_SIZE
 #define MAX_BUFFER_SIZE         FIRMWARE_MAX_PACKET
+#endif
 
 /* Locals */
 static int mStopRead = 0;
diff --git a/examples/mqttclient/mqttclient.c b/examples/mqttclient/mqttclient.c
index 8c65813a2..e390b94b7 100644
--- a/examples/mqttclient/mqttclient.c
+++ b/examples/mqttclient/mqttclient.c
@@ -34,7 +34,9 @@ static int mStopRead = 0;
 
 /* Maximum size for network read/write callbacks. There is also a v5 define that
    describes the max MQTT control packet size, DEFAULT_MAX_PKT_SZ. */
+#ifndef MAX_BUFFER_SIZE
 #define MAX_BUFFER_SIZE 1024
+#endif
 
 #ifdef WOLFMQTT_PROPERTY_CB
 #define MAX_CLIENT_ID_LEN 64
@@ -504,6 +506,8 @@ int mqttclient_test(MQTTCtx *mqttCtx)
 
         if ((mqttCtx->pub_file) && (mqttCtx->publish.buffer)) {
             WOLFMQTT_FREE(mqttCtx->publish.buffer);
+            mqttCtx->publish.buffer = NULL;
+            mqttCtx->pub_file = NULL; /* don't try and send file again */
         }
 
         PRINTF("MQTT Publish: Topic %s, %s (%d)",
diff --git a/examples/multithread/multithread.c b/examples/multithread/multithread.c
index 4114d4549..da4939802 100644
--- a/examples/multithread/multithread.c
+++ b/examples/multithread/multithread.c
@@ -42,7 +42,9 @@
 
 /* Maximum size for network read/write callbacks. There is also a v5 define that
    describes the max MQTT control packet size, DEFAULT_MAX_PKT_SZ. */
+#ifndef MAX_BUFFER_SIZE
 #define MAX_BUFFER_SIZE 1024
+#endif
 
 /* Total size of test message to build */
 #define TEST_MESSAGE_SIZE 1048 /* span more than one max packet */
diff --git a/examples/nbclient/nbclient.c b/examples/nbclient/nbclient.c
index cf337310d..ed438aa89 100644
--- a/examples/nbclient/nbclient.c
+++ b/examples/nbclient/nbclient.c
@@ -38,7 +38,9 @@ static int mTestDone = 0;
 /* Configuration */
 
 /* Maximum size for network read/write callbacks. */
+#ifndef MAX_BUFFER_SIZE
 #define MAX_BUFFER_SIZE 1024
+#endif
 
 #ifdef WOLFMQTT_PROPERTY_CB
 #define MAX_CLIENT_ID_LEN 64
@@ -444,6 +446,8 @@ int mqttclient_test(MQTTCtx *mqttCtx)
 
                 if ((mqttCtx->pub_file) && (mqttCtx->publish.buffer)) {
                     WOLFMQTT_FREE(mqttCtx->publish.buffer);
+                    mqttCtx->publish.buffer = NULL;
+                    mqttCtx->pub_file = NULL; /* don't try and send file again */
                 }
 
                 PRINTF("MQTT Publish: Topic %s, %s (%d)",
diff --git a/examples/pub-sub/mqtt-pub.c b/examples/pub-sub/mqtt-pub.c
index 467fccee5..b6d220d39 100644
--- a/examples/pub-sub/mqtt-pub.c
+++ b/examples/pub-sub/mqtt-pub.c
@@ -30,8 +30,10 @@
 /* Configuration */
 
 /* Maximum size for network read/write callbacks. There is also a v5 define that
-   describes the max MQTT control packet size, DEFAULT_MAX_PKT_SZ. */
+ * describes the max MQTT control packet size, DEFAULT_MAX_PKT_SZ. */
+#ifndef MAX_BUFFER_SIZE
 #define MAX_BUFFER_SIZE 1024
+#endif
 
 #ifdef WOLFMQTT_PROPERTY_CB
 #define MAX_CLIENT_ID_LEN 64
@@ -381,6 +383,8 @@ int pub_client(MQTTCtx *mqttCtx)
 
         if ((mqttCtx->pub_file) && (mqttCtx->publish.buffer)) {
             WOLFMQTT_FREE(mqttCtx->publish.buffer);
+            mqttCtx->publish.buffer = NULL;
+            mqttCtx->pub_file = NULL; /* don't try and send file again */
         }
         if (mqttCtx->debug_on) {
             PRINTF("MQTT Publish: Topic %s, %s (%d)",
diff --git a/examples/pub-sub/mqtt-sub.c b/examples/pub-sub/mqtt-sub.c
index cbace383c..84d791e10 100644
--- a/examples/pub-sub/mqtt-sub.c
+++ b/examples/pub-sub/mqtt-sub.c
@@ -33,8 +33,10 @@ static int mStopRead = 0;
 /* Configuration */
 
 /* Maximum size for network read/write callbacks. There is also a v5 define that
-   describes the max MQTT control packet size, DEFAULT_MAX_PKT_SZ. */
+ * describes the max MQTT control packet size, DEFAULT_MAX_PKT_SZ. */
+#ifndef MAX_BUFFER_SIZE
 #define MAX_BUFFER_SIZE 1024
+#endif
 
 #ifdef WOLFMQTT_PROPERTY_CB
 #define MAX_CLIENT_ID_LEN 64
diff --git a/examples/sn-client/sn-client.c b/examples/sn-client/sn-client.c
index e60c1f5af..15b5a9bf1 100644
--- a/examples/sn-client/sn-client.c
+++ b/examples/sn-client/sn-client.c
@@ -36,7 +36,9 @@ static int mStopRead = 0;
 
 /* Configuration */
 /* Maximum size for network read/write callbacks. */
+#ifndef MAX_BUFFER_SIZE
 #define MAX_BUFFER_SIZE 1024
+#endif
 #define TEST_MESSAGE    "test"
 #define SHORT_TOPIC_NAME "s1"
 
@@ -215,11 +217,11 @@ int sn_test(MQTTCtx *mqttCtx)
         /* Send Connect and wait for Connect Ack */
         rc = SN_Client_Connect(&mqttCtx->client, connect);
 
-        if (rc != MQTT_CODE_SUCCESS) {                                          
-            PRINTF("MQTT-SN Connect: %s (%d)",                                  
-                MqttClient_ReturnCodeToString(rc), rc);                         
-            goto disconn;                                                       
-        }    
+        if (rc != MQTT_CODE_SUCCESS) {
+            PRINTF("MQTT-SN Connect: %s (%d)",
+                MqttClient_ReturnCodeToString(rc), rc);
+            goto disconn;
+        }
 
         /* Validate Connect Ack info */
         PRINTF("....MQTT-SN Connect Ack: Return Code %u",
diff --git a/examples/sn-client/sn-client_qos-1.c b/examples/sn-client/sn-client_qos-1.c
index cee87110a..ed57b09b2 100644
--- a/examples/sn-client/sn-client_qos-1.c
+++ b/examples/sn-client/sn-client_qos-1.c
@@ -40,7 +40,9 @@ static int mStopRead = 0;
 
 /* Configuration */
 /* Maximum size for network read/write callbacks. */
+#ifndef MAX_BUFFER_SIZE
 #define MAX_BUFFER_SIZE 1024
+#endif
 #define TEST_MESSAGE    "QoS-1 test message"
 char    SHORT_TOPIC_NAME[] = {1};
 
diff --git a/examples/sn-client/sn-multithread.c b/examples/sn-client/sn-multithread.c
index 4e7d934ee..7ca310201 100644
--- a/examples/sn-client/sn-multithread.c
+++ b/examples/sn-client/sn-multithread.c
@@ -36,7 +36,9 @@
 /* Configuration */
 
 /* Maximum size for network read/write callbacks. */
+#ifndef MAX_BUFFER_SIZE
 #define MAX_BUFFER_SIZE 1024
+#endif
 #define TEST_MESSAGE    "test00"
 /* Number of publish tasks. Each will send a unique message to the broker. */
 #define NUM_PUB_TASKS   10
diff --git a/examples/wiot/wiot.c b/examples/wiot/wiot.c
index 9c4e59da8..96b6348cc 100644
--- a/examples/wiot/wiot.c
+++ b/examples/wiot/wiot.c
@@ -41,7 +41,9 @@ static int mStopRead = 0;
 static int mTestDone = 0;
 
 /* Configuration */
+#ifndef MAX_BUFFER_SIZE
 #define MAX_BUFFER_SIZE 1024 /* Maximum size for network read/write callbacks */
+#endif
 
 /* Undefine if using an IBM WIOT Platform account that you created. */
 #define WIOT_USE_QUICKSTART