I am trying to send and subscribe data via mqtt protocol using the lwip library with an STM32F207 series microcontroller. When I define MQTT_VAR_HEADER_BUFFER_LEN as 256, I have no problem receiving data. However, when I set MQTT_VAR_HEADER_BUFFER_LEN to 512 to get larger data, the incoming buffer content is empty. How can I solve this? I need to make the Buffer_Len size at least 512.
