Lost my NAS on local network

I have been using TrueNAS for years and it was always available on my local network It was there yesterday,Friday, but today Saturday, it is no longer there.
The current version is ElectricEel-24.10.2 .
I am running LInux Mint 23.1 on a local computer, and I’ve rebooted it and the NAS box, but no luck.

How do I get it back on my local network please.

Can you reach it with ping? With ssh?

Connect a monitor and a keyboard and examine if the NAS boots at all.

The NAS is up and running, sorry I should have said that before, and I can ping it as well as logging in via a web page.

Then it is on your local network, apparently. So what exactly is the problem?

I have 4 CCTV cameras where the pictures and videos are downloaded to the relevant datasets which are on a HD in the NAS. Each day, I view the pictures and videos on my local Linux Mint computer, but I could not do that earlier today.
Anyway after a further reboot of the NAS after swapping the lan connection from 1 input to another, I can now see the NAS in the Network, in the menu of folders etc when I open up the ‘Files’.

Apologies for not doing this before.