Large payload disconnects the client

[Mis1eader-dev]

Sending a large payload, 2162 bytes as an example, disconnects the client immediately and reports -6 as an error, which corresponds to:

LWMQTT_NETWORK_FAILED_WRITE = -6

Edit: The buffer size for the client is sufficient:

static MQTTClient mqtt(128 + 48/* read */, 128 + 4096/* write */);

[Mis1eader-dev]

Upon a call to mqtt.publish(...), I notice this line:

// write bytes
*sent = n->client->write(buffer, len);

First returning 25, and then returns a 0 and ends up setting the error code to LWMQTT_NETWORK_FAILED_WRITE

[joysfera]

For me, on ESP8266 it almost always disconnects while sending a large payload on the latest v2.5.2 with synchronous publish, while on ESP32 it's stable. Same source code. I've got delay(10) after client.loop(), no help.