Score:0

Ubuntu won't detect 100mbps ethernet conection

hr flag

So recently I bought a new machine and installed ubuntu on it. I connected a 1000mbps ethernet connection to it. Later for some reason, I had to connect to a different ethernet connection that has only 100mbps. Now the machine won't detect the new 100mbps connection. Ubuntu shows "Cable unplugged". But I if connect the previous 1000mbps connection, it works. I checked and the later 100mbps connection is not faulty and works on different machines. So I presume, there is some problem/configuration in ubuntu that only accepts the 1000mbps connection and not others. How do I solve this?

Output of ip a

1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host 
       valid_lft forever preferred_lft forever
2: eno1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state UP group default qlen 1000
    link/ether 3c:ec:ef:83:6e:90 brd ff:ff:ff:ff:ff:ff
    altname enp96s0f0
    inet 192.168.31.248/24 brd 192.168.31.255 scope global dynamic noprefixroute eno1
       valid_lft 80859sec preferred_lft 80859sec
    inet6 fe80::b8c7:a5b7:d509:df63/64 scope link noprefixroute 
       valid_lft forever preferred_lft forever
3: eno2: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc mq state DOWN group default qlen 1000
    link/ether 3c:ec:ef:83:6e:91 brd ff:ff:ff:ff:ff:ff
    altname enp96s0f1

EDIT 2: contents of /etc/netplan/01-network-manager-all.yaml

# Let NetworkManager manage all devices on this system
network:
  version: 2
  renderer: NetworkManager
ch flag
Could you provide output of `ip a` command?
koushik naskar avatar
hr flag
@Serg updated the answer with the output of the command
ch flag
You have 2 network interfaces - are they identical? I mean both are Ethernet and both are integrated into motherboard (or both are identical addon cards)?
koushik naskar avatar
hr flag
I has two different ethernet port
ch flag
So could you provide your `/etc/netplan` contents. And did you check both cards for this issue? Are they behaive identically?
koushik naskar avatar
hr flag
Question updated. Both the network card have same issue.
Score:0
ch flag
  1. Make sure you are using serviceable Ethernet cable.
  2. Install ethtool.
  3. Run sudo ethtool eno1 and check Supported link modes, Advertised link modes and Supports auto-negotiation/Auto-negotiation:
    Supported link modes:   10baseT/Half 10baseT/Full
                            100baseT/Half 100baseT/Full
                            1000baseT/Full
    Supports auto-negotiation: Yes
    Advertised link modes:  10baseT/Half 10baseT/Full
                            100baseT/Half 100baseT/Full
                            1000baseT/Full
    Advertised auto-negotiation: Yes
    Auto-negotiation: on
  1. In case you have no connection, run this command on another computer where you have connection with problem port and check correspondent values for Link partner:
    Link partner advertised link modes:  10baseT/Half 10baseT/Full
                                         100baseT/Half 100baseT/Full
    Link partner advertised pause frame use: Symmetric
    Link partner advertised auto-negotiation: Yes
    Speed: 100Mb/s
    Duplex: Full
    Auto-negotiation: on
  1. If both have compatible modes try to change your card parameters to meet link partner's parameters using ethtool change command as seen in its help:
        ethtool [ FLAGS ] -s|--change DEVNAME   Change generic options
        [ speed %d ]
        [ lanes %d ]
        [ duplex half|full ]
        [ port tp|aui|bnc|mii|fibre|da ]
        [ mdix auto|on|off ]
        [ autoneg on|off ]
        [ advertise %x[/%x] | mode on|off ... [--] ]
        [ phyad %d ]
        [ xcvr internal|external ]
        [ wol %d[/%d] | p|u|m|b|a|g|s|f|d... ]
        [ sopass %x:%x:%x:%x:%x:%x ]
        [ msglvl %d[/%d] | type on|off ... [--] ]
        [ master-slave preferred-master|preferred-slave|forced-master|forced-slave ]
koushik naskar avatar
hr flag
Okay so in the problematic computer both the link modes show `1000baseT/Full` only. Now how do I change this ?
koushik naskar avatar
hr flag
Tried with `sudo ethtool -s eno1 advertise 0x03f`, but it shows `Cannot set new settings: Invalid argument`
ch flag
Try debug or verbose option to obtain more details on this error.
ch flag
I think you need to use the following command: `sudo ethtool -s eno1 advertise 0x001/0x002/0x004/0x008/0x010/0x020`
ch flag
Also check with network card manufacturer or driver manufacturer do they really support other than 1000baseT.
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