Shelly button1 Action URL not working

I configured my Shelly button1 to use the Actions URL to be hit when the button is pressed short as follows;

http://192.168.2.198:8123/api/webhook/201

I'm using Home Assistant to receive this webhook call and have tested from the terminal of my computer using the following command;

curl -X POST http://192.168.2.198:8123/api/webhook/201

The command sent from the terminal of my computer works every time. When I press the button on my Shelly button1 it doesn't work.

Current version: 20201124-092005/v1.9.0@57ac4ad8

Shelly button 1 IP: 192.168.3.250/24 (Mask: 255.255.255.0, Gateway: 192.168.3.1)

Computer IP: 192.168.3.232/24 (Mask: 255.255.255.0, Gateway: 192.168.3.1)

Home Assistant: 192.168.2.198/24 (Mask: 255.255.255.0, Gateway: 192.168.2.1)

Home Assistant OS 5.10

core-2021.1.5

Am I doing something wrong here?

Thanks,

Rob