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Ethernet problems on Kubuntu 20.04.3

gr flag
Ciccio Grana

EDITED, see bottom.

this morning, after rebooting the computer, I started having a lot of connection issues on my computer. The machine is wired, but when I restarted it it couldn't set a network address, finally giving me the message eno1: IP configuration was unavailable. I am able to connect with a wireless network adapter.

A bunch of info. In my router (at address 192.168.0.250), I assigned a fixed IP to the machine, 192.168.0.150. Here's the output of a bunch of commands (only content relative to the wired interface)

$ sudo lshw -C network
 *-network                  
description: Ethernet interface
product: Ethernet Connection I217-LM
vendor: Intel Corporation
physical id: 19
bus info: pci@0000:00:19.0
logical name: eno1
version: 04
serial: 34:17:eb:ba:47:9b
size: 100Mbit/s
capacity: 1Gbit/s
width: 32 bits
clock: 33MHz
capabilities: pm msi bus_master cap_list ethernet physical tp 10bt 10bt-fd 100bt 100bt-fd 1000bt-fd autonegotiation
configuration: autonegotiation=on broadcast=yes driver=e1000e driverversion=3.2.6-k duplex=full firmware=0.13-4 latency=0 link=yes multicast=yes port=twisted pair speed=100
Mbit/s
resources: irq:30 memory:f7100000-f711ffff memory:f7139000-f7139fff ioport:f040(size=32)

$ inxi -Fz
Network: Device-1: Intel Ethernet I217-LM driver: e1000e
IF: eno1 state: up speed: 100 Mbps duplex: full mac: <filter>

$ ifconfig
eno1: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500
ether 34:17:eb:ba:47:9b txqueuelen 1000 (Ethernet)
RX packets 271 bytes 39947 (39.9 KB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 257 bytes 50551 (50.5 KB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
device interrupt 20 memory 0xf7100000-f7120000

$ more /etc/resolv.conf
nameserver 127.0.0.53
options edns0 trust-ad

$ route -n (this one is not populated when trying to connect with wired interface, putting the results for wireless just for completeness)

Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
0.0.0.0         192.168.0.250   0.0.0.0         UG    600    0        0 wlx503eaaef0caf
169.254.0.0     0.0.0.0         255.255.0.0     U     1000   0        0 wlx503eaaef0caf
192.168.0.0     0.0.0.0         255.255.255.0   U     600    0        0 wlx503eaaef0caf

Any suggestions on what could be the issue, and how to solve it?

EDIT: I feel that I probably need to add some details on the "static IP" thing. This is not something that I did on the local machine, but rather in the router configuration, and I did it for every device connected to that router and all the other devices work taking the local IP I assigned them. I did this, again, navigating to the address from which I am able to access the router configuration:

enter image description here

and then to the DHCP tab, where there is an "Address reservation" menu. From there, I reserved 192.168.0.150 to the MAC associated to my ethernet adapter:

enter image description here

As you can see from this second picture, during my troubleshooting I disabled the address reservation for the ethernet adapter, but that didn't solve the problem.

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Nmath avatar
ng flag
Nmath
Are you sure this is not a problem with your network configuration? Why did you set a static IP?
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Terrance avatar
id flag
Terrance
To go along with @Nmath above, where did you assign your system to a static IP?
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gr flag
Ciccio Grana
It is probably an issue with my config, on this machine I have a dual boot system, and under Windows the wired connection works without any problem. Additionally, other devices are connected to the router, both wired and via wifi, so it is definitely a Linux issue.
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gr flag
Ciccio Grana
I thought the static IP could be the issue (although it wasn't until yesterday), so I unassigned it from inside the router configuration and now it's free.
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Nmath avatar
ng flag
Nmath
Well again it's not clear how or why you assigned a static IP. If you define a static IP on the client side (Ubuntu) and your router has not defined the same static IP, then you will not be able to connect. The more rigid your configuration options, the less ability your network has to automatically configure itself. With automatic DHCP on the client, it doesn't matter if the router assigns a static IP to your device, but that doesn't work in reverse. Perhaps you should review your configuration options on Windows to make sure they are the same on Ubuntu
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gr flag
Ciccio Grana
I assigned the static IP from the router configuration: IP 192.168.0.150 was assigned to the MAC address of the ethernet adapter. The connection settings on the Linux side were set to Automatic, DHCP is active, and up to yesterday whenever I would turn on the computer the wired connection would activate with IP 192.168.0.150 and everything would work seamlessly.
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gr flag
Ciccio Grana
But again, that can't be the problem because in my troubleshooting attempts I went again into the router config and disabled the IP assignment, to no avail.
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gr flag
Ciccio Grana
The reason I assigned the static IP to the MAC in the router configuration is that I did it with essentially every other device in my house, so that I can define aliases for SSH'ing to each one of them without their IP changing.
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Terrance avatar
id flag
Terrance
Again, how did you assign the static IP in the system? Did you use the `/etc/network/interfaces` file? Did you use a `/etc/netplan/XX-netplan.yaml` file?
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gr flag
Ciccio Grana
I accessed my router configuration directing the browser to 192.168.0.250, navigated towards the DHCP tab, clicked on "Address reservation", and reserved IP 192.168.0.150 for the MAC associated to my ethernet adapter.
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gr flag
Ciccio Grana
I added some clarification about the "static IP" issue. I did not edit any local file to do that, no /etc/network/interfaces and no netplan.
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Nate T avatar
it flag
Nate T
Did you check the DHCP server client list to make sure that it didn't give away the ...250 ip? When you choose static, the server can sometimes reserve the ip for another device during a moment of intermittent signal. Id think this would be very rare for a constant ethernet signal, but not impossible. A reboot is more than enough downtime to make it a possibility. In your last photo, the DHCP Clients tab is where you can check... Or have you solved the issue already?
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gr flag
Ciccio Grana
The system has been rebooted a couple of times, but in any case it cannot give out IP 250: I manually limited it to addresses between 100 and 199.
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Terrance avatar
id flag
Terrance
I missed one part there, `IF: eno1 state: up speed: 100 Mbps duplex: full mac: <filter> ` shows that you are only connected at 100 Mb. :( Your NIC should be connecting at 1000 Mb. Check your cable and connection between your switch or router and the system itself. Maybe perform a power reset on your system. I have had to do that in the past to clear up network issues. Kill all power to the system and press the power button a few times, then plug in the power and power it back on.
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gr flag
Ciccio Grana
So, I fixed that part modifying manually the connection setting and power cycled every element of my netweork, computer, router and modem. No luck. Something that probably I should have said since the beginning is that recently there has been a kernel update. Thinking that that could have been the issue, I redownloaded the packages of the one I was running earlier and from GRUB I booted that old kernel, but still no luck.
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gr flag
Ciccio Grana
All right, additional details. I tried to boot into Windows, and the ethernet adapter picks immediately the connection and works perfectly, so it's not a problem of faulty cable of device. I rebooted to Linux and ran `nmtui`, when trying to activate the wired connection I get the message `Could not activate connection: Connection 'Wired Connection House' is not available on device eno1 because device has no carrier`. I read online that that "no carrier" means that either the cable is not connected (not the case, works in Windows) or that there's some driver problem.
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Terrance avatar
id flag
Terrance
Can you try `sudo dhclient -r eno1` then `sudo dhclient eno1`?
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gr flag
Ciccio Grana
The command is accepted in the first case, but with no apparent effects; and in the second case, it connects "eno1", but the connection doesn't seem to work.
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gr flag
Ciccio Grana
Additional edit: there has been an update of the kernel, but the problem is still there.
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gr flag
Ciccio Grana
Apparently [this](https://askubuntu.com/a/1233997/1127425) solved the issue. I just used `NetworkManager` as the renderer (and obviously changed the interface name to `eno1`). Thank you for the attention and time you have devolved to this.
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