Fix opentherm_gw blocks HA startup when gateway unreachable. (home-as…

…sistant#22106)

homeassistant/components/opentherm_gw/__init__.py

@@ -8,8 +8,9 @@
 from homeassistant.components.sensor import DOMAIN as COMP_SENSOR
 from homeassistant.const import (
     ATTR_DATE, ATTR_ID, ATTR_TEMPERATURE, ATTR_TIME, CONF_DEVICE,
-    CONF_MONITORED_VARIABLES, CONF_NAME, EVENT_HOMEASSISTANT_STOP,
-    PRECISION_HALVES, PRECISION_TENTHS, PRECISION_WHOLE)
+    CONF_MONITORED_VARIABLES, CONF_NAME, EVENT_HOMEASSISTANT_START,
+    EVENT_HOMEASSISTANT_STOP, PRECISION_HALVES, PRECISION_TENTHS,
+    PRECISION_WHOLE)
 from homeassistant.helpers.discovery import async_load_platform
 from homeassistant.helpers.dispatcher import async_dispatcher_send
 
@@ -115,14 +116,18 @@ async def async_setup(hass, config):
         DATA_GW_VARS: pyotgw.vars,
         DATA_LATEST_STATUS: {}
     }
-    hass.async_create_task(connect_and_subscribe(
-        hass, conf[CONF_DEVICE], gateway))
     hass.async_create_task(register_services(hass, gateway))
     hass.async_create_task(async_load_platform(
         hass, 'climate', DOMAIN, conf.get(CONF_CLIMATE), config))
     if monitored_vars:
         hass.async_create_task(setup_monitored_vars(
             hass, config, monitored_vars))
+
+    def schedule_connect(event):
+        """Schedule the connect_and_subscribe coroutine."""
+        hass.async_create_task(
+            connect_and_subscribe(hass, conf[CONF_DEVICE], gateway))
+    hass.bus.async_listen_once(EVENT_HOMEASSISTANT_START, schedule_connect)
     return True