Ethernet PCI Card, what to choose?

Hi,

A bit of context: I'm using both of my x16 PCI lanes for both the GPU and the Thunderbolt card. I'm a composer and I already use the built-in ethernet connector of my motherboard. But it's not enough.

I would like to set another ethernet route for high-demanding bandwidth audio transfer (Vienna Ensemble Pro, Audio Gridder). I want them to be free of any other packet (such as MIDI over the network, OSC, TCP, AVB, Internet, etc). An audio track takes up to 10 Mbits. Some of my projects get up to a hundred tracks. I need headroom.

I've been struggling to find a list of compatible PCI cards. Sadly I cannot go for the 10 Gbps ASUS as both x16 are taken (GPU and Thunderbolt card). There are only 3 x1 left. (ASUS TUF-GAMING Z490)

I'm on Catalina 10.15.7 (Opencore 7.0)

My question:
Is there a plug-n-play 2.5Gbps card working on the x1 slot?

If not, is there a 1Gbps card doing so?

Thanks for your help!
Have a lovely day