This issue is now resolved. The ICP connection data API was back online before 7 pm last night.
The outage was caused by malformed requests to the API. These requests looked like injection attempts and resulted in the registry manager blocking the EMI ICP connection data API access to the registry impacting all users of our API (including the My Meter page on the Authority website).
These malformed requests were likely made in error by the user rather than anything malicious. Their account remains blocked. I will be in touch with them this morning to ensure any code responsible is no longer running and to restore their access.
In addition, we have also added some gating code to catch malformed requests and avoid passing them through to the registry.
Thanks for your patience.