After Home Assistant as been installed, it can take a while to start please be patient it will start.

START/STOP/RESTART HOME ASSISTANT

sudo systemctl stop homeassistant.service

Replace stop with start or restart to get the desired functionality.

To get the current state of the homeassistant.service replace stop with status.

or you can look at amahi home server page then setting then server look for Home Assistant Server you can stop or restart on this page if needed