John, I'm in a similar position. I have a Netgear ReadyNAS Duo which is at least 10 years old and out of support. I spent some time speccing up a replacement and if it helps I eventually selected:

Synology DS220j 2 Bay Desktop NAS Enclosure with 2 x Seagate 4 TB IronWolf 3.5 Inch Internal Hard Drive

However, I didn't buy them! I looked at the cost of cloud storage and decided to get 100GB of Google Drive storage for £16 a year. This easily covers the backup of the documents folder of my laptop, leaving the ReadyNAS as a dedicated media server. I have bought a couple of caddies with 2TB SSD drives (from old laptops) that I use to back up the NAS. I shall review it next October when the Google storage is due for renewal.

I notice you currently have a WD system. Over the years, for me, Western Digital HDDs have had the most failures.

2011 Morgan 4/4
1932 Austin 7 Chummy