Faced with Internet issue: we have a 1000 Mb Lan in office, PC motherboard Lan card supports 1000 Mb Lan but Lan wire was damaged / cut and works only on 100 Mb speed. Therefore after PC start Lan Card trying to connect on 1000 Mb speed but can’t and PC couldn’t connect to the Lan.
For successfully connection Lan Card should using 100 Mb speed. Therefore, until the repaired wire we can use this workaround (manually set Lan Card speed):
sudo ethtool -s eth0 speed 100 duplex full
This command will set adapter speed to 100 Mb. Of cause you should know your interface (in my case it was eth0) and connection type (in most cases full duplex enough). This configuration will be erased after reboot therefore if you need this options from start – put them to any start script.