networking – Ethernet cannot connect

I don’t have external WiFi and ethernet is my only source.

I can’t copy and paste anything since I am on a MacBook at the time of writing this.

My other PC is running into this issue (Ubuntu 20 + 21). Please help! I have tried that touch /somePlace/10-globally-managed-something.something thingy and it still can’t connect.

Will be online tomorrow at 7/8am (GMT timezone) so I’ll be accepting solutions till then.

PC is running Ubuntu 20.04 LTS (I also tried Ubuntu 21.02 but didn’t work). Ethernet is 1GB max and it worked before on Ubuntu but not now. I am also dual booting with Windows 10, Ethernet works on Windows 10.

ethernet – Maximum length of **Stranded** Cat5/Cat5e/Cat6 cable

I know that a network cable run should not be more then 100 meters. I also understand that solid core cable has better transmission characteristics then stranded cable.

Looking online however, I was surprised that I could not find any statements about the maximum (or even a rule-of-thumb maximum) for stranded cables. The longest stranded cable length I found for sale was about 66 meters (200 feet), and the longest stranded ethernet my (reputable and knowledgeable) wholesaler seems to sell is 50 meters. This sort of implies that the maximum length for stranded cable is shorter 100 meters?

Can anyone provide insights/advise the practical limit(s) on stranded copper cable / patch lead length?

network – Mac Pro tower (2020) ethernet doesn’t work if plugged into an unmanaged switch

I’m trying to connect my Mac Pro tower (2020) to my network using ethernet but am experiencing problems if use my Netgear GS105 switch, this setup results in the MacPro saying “Cable connected but self-assigned IP”. I’ve renewed DHCP leases, changed all sorts of settings including on my router but nothing works, I have also validated that this setup does work fine with every other computer (including a MacPro Trashcan) and if I connect the MacPro Cheese-grater directly to the router it works so to recap:

This does not work:

(Router)–<cable_a>–(Switch)–<cable_b>–(MacPro2020)

This does work:

(Router)–<cable_a>–(Switch)–<cable_b>–(MacPro Trashcan)

These also work:

(Router)–<cable_a>–(MacPro2020)

(Router)–<cable_b>–(MacPro2020)

I’ve also tried different cables in place of both <cable_a> and <cable_b> and it doesn’t improve the situation, every possible combo works except if I have the MacPro 2020 Tower plugged in via the Netgear switch. Is there some issue with unmanaged switches and MacPro 2020 Towers?

How to trick my computer that it is connected to an ethernet cable?

I am currently using PDANET+ to use internet via USB tetherting. I use am using this to tether my VPN connection. The problem is it does connect me to the internet, but it doesn’t show that I am connected to the internet so when I play online games It is disconnecting.

performance – Slow file transfer speeds over gigabit ethernet

Within my setup are:

  • 1 FTTP router with Cat5e internet cable out
  • 1 Netgear GS308E gigabit switch, connected to the router via Cat6.
  • 2 devices (1 Raspberry Pi4, 1 thinkpad with gigabit ethernet connection), both connected to the switch via Cat5e and Cat6 cables respectively.

The RPi4 as 2 external USB 3.0 WD Passports connected to USB 3.0 ports.
The thinkpad has an internal SSD.
The RPi4 also has a gigabit ethernet connection.

When copying files from the RPi4 to the thinkpad using either scp or wget, I receive an average speed of 4.3MB/sec.
The sample file used in an ISO image with a size of 4GB.
For wget, The RPi4 hosts a temporary web server using python -m SimpleHTTPServer.
I’ve tested internal copying on the RPi4 from one WD passport to another, and from one WD passport to the RPi4 local SD card, and according toiotop, I’m gaining write speeds well over 20MB/Sec and read speeds between 50MB/Sec and 80MB/Sec.

I don’t know of any software configuration either on the router, switch or the source and destination devices that could be throttling the transfer speed.

What other options can I take to further diagnose the issue?

networking – ethernet not working after reboot on Ubuntu Server 20.04.2

I had an ethernet connection successfully working, but now after a reboot it’s no longer working.

sudo lshw -C network reveals

*-network ... 
  description: Ethernet interface ...
  ... 
  product: RTL8111 ...
  ... 
  logical name: enp4s0

cat /etc/network/interfaces is empty

ip link show reveals

  2: enp4s0:  ​... state DOWN mode DEFAULT
    ... link/ether

after sudo ip link set enp4s0 up
, then ip link show reveals

2: enp4s0:  ​... state UP mode DEFAULT
     ... link/ether

but still, ping 192.168.0.1 results in ping: connect: Network is unreachable

/etc/netplan has a file called 00-installer-config.yaml with contents

network:
  ethernets:
    enp3s0:
      dhcp4: true
  version: 2

N.B. I don’t currently have ifconfig or net-tools installed

What should I try to get my ethernet connection working again?

linux – Boot desktop PC from SSD installed in Laptop over ethernet

For work I mainly use a Laptop (OS is Ubuntu 20.04), because I need to be mobile. However, when I am at home I also have a powerful desktop PC (also running Ubuntu 20.04) which I prefer to use to compile large software projects, as it is much faster.
Since I often switch between Laptop and PC I need to keep all my files synchronized (documents, browser bookmarks, etc.) which is of course possible, but I would like to achieve a more comfortable solution.

Would it be possible, to not use the SSD installed in the PC at all, but boot from the SSD installed in the laptop instead directly? For example with boot over ethernet? Then I could use the computing power of the PC and when I need to take my laptop with me I don’t need to remember synchronizing it, because I use the same SSD anyways.

My laptop is a Lenovo ThinkPad T14s AMD (1Gbit ethernet) and the desktop PC is an AM4 platform with 2.5GBit ethernet adapter.

I am happy to provide more details if necessary. Not sure if what I would like to achieve is possible at all. I am willing to buy additional hardware if needed (e.g. a switch?).

Cheapest unmanaged 10GE (10Gbit Ethernet) switch?

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linux – Ethernet (wired connection) is Unreachable in Ubuntu 20.04

I have Ubuntu server where I have configured the static IP it was pinging and able to update and use internet and able to connect through ssh. but after the shutdown because of power failure. I was not able to ping and unable to use ssh.

When I enter command ip addr show it doesn’t show the configured ip address

$ ip addr show eth0
eth0: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc pfifo_fast state DOWN   
group default qlen 1000 link/ether 3c:97:0e:11:22:0d brd ff:ff:ff:ff:ff:ff