MyCadet is only accessible when you are in the United Kingdom.
If you are currently outside of the United Kingdom, you will not be able to access MyCadet.
You will see an error message that mentions 'Attack ID: 20000018'
You may also see this error message if you are using a VPN (Virtual Private Network) to access the internet, as this may identify your device as being outside the UK.
To access MyCadet, you either need to return to the UK or disable your VPN.