Ubuntu – Ethernet connection not working on Ubuntu 20.04

20.04ethernetnetworking

A few days ago my ethernet connection was not working on Ubuntu 20.04 on my computer. I was using two routers: the main one was / is in the living room and connected to the second router which was / is in bridge mode and the second router was connected to my computer. Thanks to @heynnema, I found out the cause of the problem was the second router. When I connected the main router directly to my computer, the ethernet worked.

Yesterday, my father and I connected the second router to another PC at home. (The main router and my computer is still directly connected together but the other PC is connected to the second one and the second router is connected to the main one.) But then the ethernet on my computer started not working again. It only works when the second router isn't connected altogether. I want the second router to work because I can't connect to WiFi in my bedroom without it because the WiFi range of the main one is too small. What should I do? I have no problem with the connection on Windows 10.

Edit: sudo lshw -c network output: https://imgur.com/a/43I3Ki5

Edit 2: I installed Linux Bash Shell on Windows 10 and wrote sudo lshw -c network again. Here is the output: https://imgur.com/a/5gHODNr And the output of ip a: https://imgur.com/a/cVcO5cC

Best Answer

Router/cabling problem

modem--> main router--> secondary bridged router--> PC

Your ethernet link speed is only 100Mbs. It's capable of 1Gbs. Check that you're using cat 5e or cat 6 cables. Check that your routers support 1G LAN ports.

After moving the cat 5e cable from computer directly to your main router, from the secondary bridged router, ethernet now works. Check your configuration of the secondary router.

Netplan

Change your /etc/netplan/01-network-manager-all.yaml file to look like this:

network:
  version: 2
  renderer: NetworkManager

sudo netplan generate

sudo netplan apply

reboot

Then use the NetworkManager applet to connect to the "Wired Connection".

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