You can enable debug for Ajax plugin in jeedom. Then in Analysis->logs every request will be displayed.
Every outgoing call start from ha_direct_call
Is request present in Jeedom log, after you saw “failed to connect” message? What HA log say, maybe there is more info?
When your ARM already armed system - api will not send any answer. So I add ARM switch, wich follows current arm status. It’s better to use switches, instead of buttons.