in 9_3_MQTT_Client_1.ino between line 64 and 65
xTimerStop(wifiReconnectTimer, 0);
needs to be added.
(same for 9.4 between line 81 and 82)
The ESP_client_1 is establishing
a new WIFI connection,
a new connection to the MQTT broker and
a new subscribtion
every 2 seconds
in 9_4_MQTT_Client_2.ino
line 214
mqttClient.publish(“esp32/led”, 0, true, “toggle”);
the retain flag (3rd argument) is set to true
As a result the ESP_Client_1 gets a toggle message
every 2 seconds and the led is blinking
Adding the mentioned line fixes the problem