AlarmDecoder won't arm or disarm although CON ADR 18 is free

My AlarmDecoder won’t arm or disarm my Vista 21ip LTE. I have six other keypads that function fine. CON Address 18 is open, since that’s the factory setting for the AlarmDecoder. The HA Alarm Display shows the armed and disarmed status properly, as well as the status of all my sensors. When the alarm is tripped, it shows that status and properly sets off an automation.

Are you running the latest firmware on the AlarmDecoder?

As far as I know. The device works fine when I run the PC App on a laptop.

Is there a way to use Home Assisant’s Terminal program to see what the firmware version is? I bought the device in Nov, 2021.

https://www.alarmdecoder.com/wiki/index.php/Firmware

Connect the AlarmDecoder to a computer. It will show up as a COM port. Use a terminal program at I believe 115200 N,8,1.

Issue the V command and it will spit back the firmware version.