Using the Xplenty add-on with Private Spaces database, we need to know which IP addresses to grant access to.
Datastores within private spaces are private by default, meaning that external access (even to add-on providers) is not permitted initially.
In order to use external connections to a private spaces database, you will need to enroll in the Trusted IPs for Data Services program: https://devcenter.heroku.com/articles/private-spaces#trusted-ip-ranges-for-data-services
With this in place you need to grant access to the IPs used by Xplenty in order to have their add-on work. You can find a list of their current IP ranges here: http://community.xplenty.com/knowledgebase/articles/614346