Downstream Issuer system is down: The gateway or downstream is temporarily unavailable, preventing payment authorization.
Connectivity issues with the issuer: The payment gateway is unable to establish a stable connection with the issuer's network.
Issuer undergoing maintenance: The card issuer may be performing scheduled or unscheduled system maintenance.
Temporary technical fault: A transient system error at the issuer's end is preventing transaction processing.
Advise the customer to retry the transaction after some time using the same card.
If the issue persists, suggest using a different payment method or card.
Monitor the gateway's status for any ongoing outages or maintenance notifications.
Contact the payment gateway support team if this error occurs frequently to confirm connectivity with the issuer.