Any tips for tricking a Netgear ReadyNAS into responding with an external IP address to an iSCSI request when it's inside a NAT?

General comments suggesting against iSCSI over WAN?

Otherwise I need a Veeam Wan Accelerator server on each end ...

NAS = Network Attached Storage
NFS to UNIX/Linux or CIFS to Windows [and Linux]. This exports filesystems to your servers which can mount as the NFS or CIFS type filesystem.

SAN = Storage Area Network
This presents LUNs to your server as if they were disks (not filesystems like NAS) so that you can use the device as you would a local disk (e.g. Partition it, Add it to LVM, Use as a Metadisk).

iSCSI is LAN based topology for presenting SAN to your servers rather than using fiber scsi or plain old SCSI traditionally used by SAN. Many storage arrays these days can do either fiber or iSCSI but some only do one or the other.

Given its name I'd think your ReadyNas couldn't do iSCSI as it is a NAS Appliance rather than a SAN storage array.

Finally: Doing storage over a WAN at best is going to be slow and at worst is going to have lots of network issues. There are methods for doing storage objects to cloud that perhaps you could adapt but were it me unless I absolutely had to do so I wouldn't go down that path. It would require much research starting with whether you in fact have NAS or SAN.

I'd consider some sort of tunnel to the nas if I had to use that transport. Usually one might consider other means to deliver resources.

Some soho routers have features already in place.

Of course you will have to watch any sort of IP changes.

SMB/CIFS is a plan B (or plan Z) that would entail an extra Veeam Enterprise Plus server at each location running a WAN Accelerator server.

NFS is possible but not viable. Among other reasons, Linux NFS implementations are pathologically bad, and the NAS NFS drivers are not much better. On Unix, or even Windows, I would consider NFS, with careful parameter tuning. It's certainly designed to be robust over network connections.

Thanks!