Issue with mqtt

hi, I just got a new raspberry pi 3b+. installed the hassbian image and all worked out well. I changed password and localization then added samba. then I went into the configuration.yaml file and added mqtt: once I restart the my tasiota device connects. once I go back to the configuration.yaml file and add the switch and restart, io get the following error from the terminal of the Sonoff.

15:38:48 MQT: Attempting connection…
15:38:53 MQT: Connect failed to 192.168.1.151:1883, rc -4. Retry in 10 sec

it does connect. but stops once I restart home assistant and never seems to connect.

can someone please help me!!

Googling finds this https://github.com/arendst/Sonoff-Tasmota/issues/448