However when I try to generate a certificate I get an error. Now unraid helpfully talks about this error and it can be overcome by disabling DNS rebinding protection on the router but I have found no setting like this on my router. The full spiel from unraid is below:
Many routers have a security feature known as DNS Rebinding Protection. This feature prevents public DNS entries from pointing to local IP addresses on your network. Unfortunately, this feature prevents us from providing proper SSL access when connecting to the webGui locally. As such, users must either disable this feature on their router or set their router to allow DNS rebinding for the unraid.net domain. Depending on your router, how this feature is described and whether or not it is available to configure may vary. In addition, once you have DNS rebinding disabled on your router, when you go to provision your certificate, you may still see the DNS rebinding error message the first time. This is due to the time it takes for DNS records to propagate once provisioned.