RAXE500 NAT loopback/hairpinning?

I just got and set up my RAXE500. I use a Synology NAS with a DDNS address (think myNASexample.synology.me), and access it that way generally. I have found myself unable to access it via the URL I use despite it still working when on other external networks. Googling indicates to me this is because the router is not doing hairpinning/NAT loopback. I saw there is a compatibility list, which does not include the RAX500, but does include the predecessor, the RAX200.

I find it weird the upgraded model would be missing a feature like this. Am I missing something and there's somewhere to enable it, or will it be coming in a future firmware update? I'm on 1.0.9.78, which I believe is the latest firmware.