2x EXT2 on same network

So the second EXT2 arrived today, I bought one to test and liked it’s performance and lack of crappy bloaty mcbloat rubbish.

The 2nd is going to backup the first. If I can get it working.
I’m getting the rsync error when trying to browse the destination folder setting up a remote backup. But both units are on the same network and subnet, so I’m not going ‘through’ the router, so I shouldn’t need to setup any forwarding surely? How should I address the destination unit on the same network?

Could someone please confirm for me?
Many thanks.

Are you using sshd user? If you try ssh sshd@remoteIP from the “old” NAS, can you connect to the remote NAS successfuly? What is the rsync error?

If you run the command arp -a can you see your remote nas?