Readynas IP address wrong - how do I change it (Mac)

Alright, so it looks like the NV+ has a static IP and the two other NAS are on DHCP (meaning they picked up the new IP address from the new network automatically).

You should be able to just reset the network of the NV+ back to DHCP. Just perform an OS re-install on the NAS (this will also reset the password back to the default password). Careful not to select factory default! as that will wipe all data.

If you have an NV+ v1, you can enter the boot menu and do an OS re-install this way:
https://kb.netgear.com/24874/How-do-I-access-the-boot-menu-on-my-ReadyNAS-Duo-NV-NV-X6-or-600
NV+ v1 default password: netgear1

If you have an NV+ v2, you can do it this was via the boot menu:
https://kb.netgear.com/20853/How-do-I-access-the-boot-menu-on-my-ReadyNAS-NV-v2
NV+ v2 default password: password

How do you determine whether it is an NV+ v1 or v2 that you have? Looking at the colour of the chassis is an easy way. Is it silver colour with green-ish display? Then it is a v1.
https://www.netgear.com/support/product/RND4000v1_(ReadyNAS_NV_plus_v1).aspx

It is more of a metalic grey colour and has "ReadyNAS NV+ v2" written on the front of it, then it is a v2.
https://www.netgear.com/support/product/RND4000v2_(ReadyNAS_NV_plus_v2).aspx


Cheers