Access ReadyNas 102 via Hostname

I have my nas box creatively named "nas"

But cannot access it via that name, https://nas/ and http://nas/ both return "site cannot be reached"

And ping :

$ ping nas
ping: cannot resolve nas: Unknown host

I read and have seen on another one, that the hostname should be reachable.

How can I configure this for all devices on my network (ie not just update my /etc/hosts file!)

Accessing via a R7000 – Nighthawk AC1900 Smart WiFi Router

Note sure if this is related to another issue I have raised here https://community.netgear.com/t5/Using-your-ReadyNAS/Cannot-access-admin-via-https/m-p/1368885

I know that I used to be able to access my device via "nas" in the URL bar, so I am not sure why its not working now.