> I've had great luck with Realtek NICs, although I don't specifically recall using their USB NICs.
I envy you. Realtek NICs (especially over USB) are tantamount to trash in my mind after 2 decades of fighting their frequent failures. Be it failure to initialize at all to driver crashes to pisspoor feature sets (or claiming to have features that don't work at all), and a myriad of other problems. Granted, they usually work in Windows, but I don't work in windows (I live and work in linux/BSD). It has become my personally policy to avoid/disable and realtek NICs and replace them with something actually functional whenever possible.
Hopefully their work on linux-side drivers will change this given their proliferation.
To be honest I've yet to find a reliable USB based network interface regardless of chipset/brand/manufacturer, outside of the ones that do PCIe passthrough via USB4/Thunderbolt and those tend to be quite expensive (though they are starting to come down in price).
The problem with USB NICs is now you have two flaky failure points - the chipset driving the USB port and the chipset driving the USB network interface.
I had a reliability issues using a Realtek 2.5 Gbps USB network interface. Kept locking up, or having latency issues. Until I switched which USB port I plugged it into (one that used a different chipset), and after that it was solid.
Realtek itself (Questionable quality on a good day)
The implementation of Realtek by the ODM/OEM/SI into whatever part is being shipped, which given Realtek is the defacto "budget" option for networking, it's often done as cheaply and shoddily as possible, even if the chip itself actually isn't crapware.
And the USB interface as you point out. There's a whole rabbit hole that I'm unfortunately all too familiar with when it comes to diagnosing and dealing with USB. PCIe passthrough via a USB4/TB combo chip isn't as reliable as just using PCIe directly, but it's still better than a non-pcie passthrough usb interface.
They use the USB-C physical interface for their modules, but that doesn't mean they actually use the USB protocol on the backend. Not sure how they implement it to be honest, but it's at least entirely possible for example to run display-port only (With no USB involved at all) through a USB-C PHY (and dp isn't alone in being able to do that).
I suspect a lot of the flakiness is not the chip itself but the fact that, because it's cheap, the bottom-of-the-barrel manufacturers will always use it instead of the significantly more expensive alternatives, and then further cut corners with the board layout and design.
Ironically, the only problems I've had with NICs were on an Intel and a Broadcom.
> I suspect a lot of the flakiness is not the chip itself
Most certainly. Doesn't change the fact that Realtek being present is a huge redflag, even if it's not a cheap device, regardless of whether it's realtek's fault or the OEM/ODM/SI that integrated them into the system in question. It basically screams "we phoned this part in", though it's certainly not always true, it's true enough that I refuse to use them (be it by disabling them or just opting for entirely different hardware so I can avoid that headache).
Broadcomm is certrainly better than Realtek, but it's still a "Replace at soonest possible convenience" tier as well. Intel is far far more reliable in my experience (save for some of their combo bluetooth/wifi cards, but their dedicated wired ethernet cards have always been great for me. The i210/211 class of integrated bottom tier ones can be hit and miss though.
I envy you. Realtek NICs (especially over USB) are tantamount to trash in my mind after 2 decades of fighting their frequent failures. Be it failure to initialize at all to driver crashes to pisspoor feature sets (or claiming to have features that don't work at all), and a myriad of other problems. Granted, they usually work in Windows, but I don't work in windows (I live and work in linux/BSD). It has become my personally policy to avoid/disable and realtek NICs and replace them with something actually functional whenever possible.
Hopefully their work on linux-side drivers will change this given their proliferation.
To be honest I've yet to find a reliable USB based network interface regardless of chipset/brand/manufacturer, outside of the ones that do PCIe passthrough via USB4/Thunderbolt and those tend to be quite expensive (though they are starting to come down in price).