Information to tell merchant and provide to their IT team:
For network connection credit card terminals, a key thing should be verified network wise with the customer and their IT.
Is there a firewall in place on the network with restrictions?
If so then the need for whitelisting INBOUND and OUTBOUND traffic needs to be discussed, as well as GeoIP filtering INBOUND and OUTBOUND.
URLs for Whitelisting on the firewall:
*.adyen.com
*.adyenpayments.com
GeoIP filtering for the following countries:
Netherlands
Germany
The GeoIP filtering is needed because our partner Adyen has server calls that go back to those countries.