Looks like this week the IPN notifications have been very delayed. A sale will happen and then the IPN historical dashboard will show the transaction in a retrying state for up to 6 times or so with NO HTTP status code. Sometimes the IPN packet comes through in a minute, other times it comes in a whole hour after the transaction occurs. This is causing big problems for us.
I know it's not our server as I've checked all the server logs and there is only ever ONE attempt to call our IPN handler (notify.php) and it always returns a status 200 and works fine. This is obviously the last retry attempt (again, up to an hour after the purchase sometimes). Every attempt by PayPal to resend the packet doesn't actually do anything. It's not our firewalls/WAF/security systems either as we setup logging to track all packets and it only ever comes in just one time - just very delayed.
So what's going on PayPal with the IPN systems? Can we please get this resolved?
