Lan card compatibility, about QXG-10G1T spec

Looking for compatible 10G lan card for TVS-h874.
In compatibility list

2nd row
QXG-10G1T
Single-port (10GBASE-T)
10GbE network expansion card, Aquantia AQC107S, PCIe Gen3 x2, low-profile bracket pre-loaded, low-profile flat and Full-height are bundled

2 row before last
QXG-10G1T
Compatible only with PCIe slot #1.
Single-port (10GBASE-T)
10GbE network expansion card, Aquantia AQ107, PCIe Gen3 x4, low-profile bracket pre-loaded, low-profile flat and Full-height are bundled

Same QXG-10G1T is explained different.
I want to know whether this card can be used on slot#2.

There is apparently different versions of that card with different lenght PCI-E slots. (see your post)

To make sure, open a ticket

Thanks for reply, as you mentioned, one is PCIe Gen3 x2 and the other is Gen3 x4.
But question is, how do I distinguish 2 different model with same model name?
Or is the PCIe Gen3x2 is EOL and most of the card in market is Gen3 x4?

These cards were sold out for a while…the older controller type is probably only available on very old stock…you can check the specs with QNAP support or the reseller

or - you can simply purchase a QNAP QXG-10G2T, which is a compatible dual port 10G card, that I assure you works. You should have purchased that when you first got the TVS-h874. OR, if you intend on adding in a 3rd computer in the future - just leave what you have, and purchase a small 10G switch, so you will be set for the future, instead of making lots of tiny purchases (that add up to the price of a small 10G switch).
Bob