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Today I got my 500 Mbits line, at the beginning ethtool was set to 100Mbits so I didn't get the full speed.

After I had unplugged and plugged in again, 1000 Mbits was displayed.

Just now the Internet was briefly interrupted (for whatever reason) and I found this setting back to 100Mbits.

How can I set that the speed is not always automatically adjusted here and remains at 1000 Mbits?

Thanks in advance.

Omexlu
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  • Have you looked in /var/log/syslog the speed of your network connection is negotiated and any drop in speed should be reported. It sounds as though your cable is loose or faulty, is it cat6e or a good cat5e cable? Try changing the cable and see if it is more stable – SEWTGIYWTKHNTDS May 14 '21 at 10:31
  • The cable is a cat5e, nothing strange with the wire, at the moment it works, i the logs i can only found that May 14 09:04:55 XXX systemd-udevd[438]: ethtool: autonegotiation is unset or enabled, the speed and duplex are not writable., i can't disable autoneg with ethtool, after the command sudo ethtool -s eno1 autoneg off speed 1000 duplex full auto-negation is still enabled. – Omexlu May 14 '21 at 10:52
  • I haven't had an issue with auto negotiation, it usually works very well. You said that the 500M connection is new, if the router is new too then maybe it has a faulty port, if it has more than one you could try plugging into another port. I run at 1 gig over cat5e but my cables are < 5 meters and good quality. It could still be your cable, if you have another it might we worth a try. Hope you get it sorted – SEWTGIYWTKHNTDS May 14 '21 at 11:04
  • Until now i doesn't happen again, i need to check that the next days, the cable and router are not new, now i am on full-speed. Maybe the network-card is faulty? If it happends again in next time, is it worth to buy an extern card like that?: https://tinyurl.com/networkCardAskUbuntu

    If it happends again, maybe i can check it trought a script an force the setting?

     – Omexlu May 14 '21 at 11:09
  • Agree that cable or connections could be the problem. Removing and reinserting the cable like you did could dislodge some debris or dust, or just make a better connection. Bends in cables can affect the negotiation. 1G standards expect autonegotiation at both ends. Unless you have control over the speed/duplex settings at both ends it isn't advisable to manually set or disable autonegotiation. Cheaper to try another cable than to replace a NIC. – jtessier72 May 15 '21 at 10:22

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