I'm hardly getting 100--140Mbps on my Pi4 (model B rev. 1.4 at 8GB ram) through wired ethernet cat 8 connection to a 2.5Gb port on my router. Plus, the upload speed is higher, reaching 350Mbps (which is wierd!)
By comparison, using the same wire and same i/o port on my router to hook up my desktop PC to the internet, I get 1GBps...
I've been reading the whole evening a certain variety of posts which expose similar situations but I couldn't manage to find the answer: Pi4 is supposed to be equipped with true 1Gb Ethernet, isn't it??
I've read about the Pi3B+ limitations due to USB bridge and also about possible interference with Bluetooth and Wi-Fi, but disabling those didn't work.
FYI the context is really simple: I'm just trying to use the Pi as a regular computer for simple online tasks such as browsing internet and watching Netflix...
I figured I could test my second RPi4 (same model, 4GB ram), but the results are very low too though they are not exactly the same : 75 Mbps download and 150 Mbps upload.
There is nothing attached to the USB ports beside keyboard and mouse, but the first RPi4 has joy-it armour on it (the big heat sync with two fans connected to the 5v pins)