Thank you @lpirlfor your tip, unfortunately it did not work on my Orange Pi PC (H3 CPU), running Armbian 22.05.1 Bullseye with Linux 5.15.43-sunxi.
Here is what I tried (as root) :
apt install tuned tuned-utils tuned-utils-systemtap
tuned-adm profile latency-performance
reboot
It happens since I changed my ISP (and the router they provide). I tried all ethernet ports, but unfortunately nothing worked
@guidolwas right, I will try to put a switch between the router and the OPi to see if it gets better!