GitHub repository: manmuqingshan/AsyncMQTT_Generic
Description: Arduino Library for ESP8266, ESP32, Portenta_H7, STM32 and Teensy 4.1 QNEthernet asynchronous MQTT client implementation. This library, ported to support ESP32, WT32_ETH01 (ESP32 + LAN8720), ESP8266, Portenta_H7 (Ethernet or WiFi) and STM32 (LAN8742A or LAN8720 Ethernet), Teensy 4.1 using QNEthernet. Currently supporting TLS/SSL for ESP32 only