Once the datas off, I’ll take out all deices and have a look around inside and see about the fans.
The nas isn’t the only storage on site, there’s a smaller bought new single drive nas, but it can’t store everything and some things went straight to the bit bucket.
I’m liking your plan. Something like a 10gb, and run it single plus probably keep two 3’s as raid 1 and manually copy data between them.