2xsaiko

It would need a PCIe slot, not a SATA connection. But I assume it doesn’t have that either then.

I have the QNAP TL-D800S. It’s an 8 bay DAS but there is also a 4 bay variant. Works well for me. It uses SFF cables to connect to the PC and comes with the appropriate PCIe card which seems more robust to me than anything USB for this.

Any registrar worth using has an API for updating DNS entries.

I just found this with a quick search: https://github.com/qdm12/ddns-updater