Hello Rob,
Thanks for your quick reply.
The problem is that our hosting server has a firewall that blocked all outgoing connections, as you guessed. We disabled it and have now managed to register the plugin and import events from eventbrite. We would like to turn it back on and whitelist the address(es) used to communicate with the eventbrite servers. If you could find these for us that would be great!
Thanks again for your help,
Kind regards,
– Tony