Hi Nazar, On Wed, May 13, 2020 at 08:58:16PM +0200, Nazar Zhuk wrote: > I have a 1Gbps network port that correctly connects as 1Gbps full duplex on > boot, then drops to 100Mbps 4 seconds later.
Negotiation is failing and that is required for 1Gbit, so I would start by ruling out the device that your computer is plugged into by plugging it into something else. A real gigabit switch would be ideal but even another gigabit port on a computer will work well enough to show negotiation, as auto-crossover (Auto MDI-X) is implemented on all but the most basic gigabit chips. If it works with other things then the conclusion is probably that your Thunderbolt hub is junk. If it doesn't work with other things then the conclusion is probably that your network chipset is junk. It would be very very unlikely to be a software issue in Debian or the kernel as negotiation is at a very low level. But if it does not work properly with other things you could try reporting it as an upstream kernel bug in the driver and see what happens. Cheers, Andy -- https://bitfolk.com/ -- No-nonsense VPS hosting