Cannot configure DDNS - Patch error

For some reason I get an error when I try to add the DDNS hostname on my account. I have checked the spelling of the hostname and it is correct and does not contain any trailing spaces or capital letters. I am using the built in dynamic DNS of my TP-Link router so the domain is something like hostname.tplinkdns.com if that matters.

The response the network request gives is just:

{"errors":[{"code":"internalServerError"}]}