I have a question. I read on this page of yours – https://nascompares.com/2019/10/07/thunderbolt-3-vs-40gbe-nas-in-2019 – that the DS3617xs can support 40GBE. Do you supply those cards? I can’t seem to find much information for 40GBE, only 10GBE. Thanks in advance!
I have tested this card on Qnap https://www.span.com/product/Qnap-40GbE-PCIe-Card-LAN-40G2SF-MLX-Dual-Port-QSFP+-PCI-Express-gen3-x8-Mellanox-CX3-~52718.
But Synology should support Intel based cards.
Here is Melanox card tested on DS3617xs-
|Mellanox||ConnectX-3 Pro EN MCX314A-BCCT|
I hope this helps.