Getting started with an Netgear ReadyNAS NV+

You'll need to upgrade the firmware to 4.1.16 (4.1.6 goes back to 2009).  Try accessing http://nas-ip-address/admin using internet explorer and see if that lets you connect (using the real IP address of course).  If that still won't work, you can download an old version of Firefox, being careful not to let it upgrade itself). The default username is admin, the default password is netgear1.

I'm not sure if the NAS will be able to find the current firmware upgrade server - if it won't, you can download the firmware to your PC, and then manually install it.  https://kb.netgear.com/000038792/RAIDiator-Version-4-1-16-Sparc  You will need to extract the firmware from the zip file and then upload it to the NAS.

After the firmware update, you should do another factory default/fresh install.  There were changes in the on-disk layout after 4.1.6, and the only way to take advantage of them is to let the NAS reformat the disks.

BTW, your NAS is limited to 2 TB drives.  It also is limited to SMB 1/CIFS.  If you use Windows 10, you will need to enable the SMB 1 client via "turn windows features on or off".  If you use a Mac, you'll either need to find a way to enable SMB 1, or use AFP.