Earlier quoted context omitted.
I own one also, while I do recommend them... I would also recommend some caution if planning to use Linux I'm not sure if this is a common/repeat thing, but for mine I need to maintain a build of the Realtek kernel modules out of tree If I try to use the discovered/automatic/inline driver... it'll drop out if I try to saturate the link. It's only when I blacklist this module and compile/use the one from Realtek that…
Based on the UK reseller, Ubuntu 20.04 supports the ethernet chipset out of the box, while 18.04 doesn't. I run on an unmodified 18.04 though (kernel v5.4), so I think that the support has been also added in a more recent 18.04 LTS patch version.
I'd be curious to know if you're connected at 1 or 2.5G, and if 2.5, how it does if held at that level for about a minute
An iperf3 test or two is usually enough to make it drop until I reboot
Where with the compiled module it's rock solid