NIC issue says "Link is up/Link is down" continuously

Question

I'm trying to make my Ethernet connection work on my Ubuntu laptop but for some reason the NIC refuses to work.

I've tried everything I know, everything I found in the internet and it still doesn't work.

Here's a list of what I tried:

• Using ethtool to change the speed and the duplex according to the Supported link mode of the NIC and the Advertised link mode of the switch and router.
• Used three different ethernet cables connected to my switch and changed ports on the switch. Every other port and cables work.
• sudo ifconfig <interface> up, sudo ip link set <interface> up but no changes.

Here is what dmesg --follow returns continuously as I run these commands:

[  916.193910] r8169 0000:01:00.0 enp1s0: Link is Up - 100Mbps/Full - flow control off
[  917.082174] r8169 0000:01:00.0 enp1s0: Link is Down
[  918.678983] r8169 0000:01:00.0 enp1s0: Link is Up - 100Mbps/Full - flow control off
[  919.564996] r8169 0000:01:00.0 enp1s0: Link is Down
[  923.672566] r8169 0000:01:00.0 enp1s0: Link is Up - 100Mbps/Full - flow control off
[  924.556212] r8169 0000:01:00.0 enp1s0: Link is Down

When I change config with ethtool it just says Link is Down and doesn't do anything anymore, especially when I run autoneg off.

Here's what sudo ethtool <interface> returns before any modification:

Settings for enp1s0:
        Supported ports: [ TP MII ]
        Supported link modes:   10baseT/Half 10baseT/Full
                                100baseT/Half 100baseT/Full
        Supported pause frame use: Symmetric Receive-only
        Supports auto-negotiation: Yes
        Supported FEC modes: Not reported
        Advertised link modes:  100baseT/Full
        Advertised pause frame use: Symmetric
        Advertised auto-negotiation: Yes
        Advertised FEC modes: Not reported
        Speed: Unknown!
        Duplex: Unknown! (255)
        Port: Twisted Pair
        PHYAD: 0
        Transceiver: internal
        Auto-negotiation: on
        MDI-X: Unknown
        Supports Wake-on: pumbg
        Wake-on: d
        Link detected: no

Whatever speed or duplex I put it at it doesn't change anything it says Link is Down.

EDIT

I tried to install the r8168-dkms package instead but that's what it says:

sudo dpkg -i r8168-dkms_8.048.00-1_all.deb
Selecting previously unselected package r8168-dkms.
(Reading database ... 295124 files and directories currently installed.)
Preparing to unpack r8168-dkms_8.048.00-1_all.deb ...
Unpacking r8168-dkms (8.048.00-1) ...
Setting up r8168-dkms (8.048.00-1) ...
Loading new r8168-8.048.00 DKMS files...
Building for 5.15.0-56-generic
Building initial module for 5.15.0-56-generic
ERROR: Cannot create report: [Errno 17] File exists: '/var/crash/r8168-dkms.0.crash'
Error! Bad return status for module build on kernel: 5.15.0-56-generic (x86_64)
Consult /var/lib/dkms/r8168/8.048.00/build/make.log for more information.
dpkg: error processing package r8168-dkms (--install):
 installed r8168-dkms package post-installation script subprocess returned error exit status 10
Errors were encountered while processing:
 r8168-dkms

Output of lspci:

00:00.0 Host bridge: Advanced Micro Devices, Inc. [AMD] Family 15h (Models 60h-6fh) Processor Root Complex
00:00.2 IOMMU: Advanced Micro Devices, Inc. [AMD] Family 15h (Models 60h-6fh) I/O Memory Management Unit
00:01.0 VGA compatible controller: Advanced Micro Devices, Inc. [AMD/ATI] Stoney [Radeon R2/R3/R4/R5 Graphics] (rev da)
00:01.1 Audio device: Advanced Micro Devices, Inc. [AMD/ATI] Device 15b3
00:02.0 Host bridge: Advanced Micro Devices, Inc. [AMD] Family 15h (Models 60h-6fh) Host Bridge
00:02.2 PCI bridge: Advanced Micro Devices, Inc. [AMD] Family 15h (Models 60h-6fh) Processor Root Port
00:02.4 PCI bridge: Advanced Micro Devices, Inc. [AMD] Family 15h (Models 60h-6fh) Processor Root Port
00:03.0 Host bridge: Advanced Micro Devices, Inc. [AMD] Family 15h (Models 60h-6fh) Host Bridge
00:08.0 Encryption controller: Advanced Micro Devices, Inc. [AMD] Carrizo Platform Security Processor
00:09.0 Host bridge: Advanced Micro Devices, Inc. [AMD] Carrizo Audio Dummy Host Bridge
00:09.2 Audio device: Advanced Micro Devices, Inc. [AMD] Family 15h (Models 60h-6fh) Audio Controller
00:10.0 USB controller: Advanced Micro Devices, Inc. [AMD] FCH USB XHCI Controller (rev 20)
00:11.0 SATA controller: Advanced Micro Devices, Inc. [AMD] FCH SATA Controller [AHCI mode] (rev 4b)
00:12.0 USB controller: Advanced Micro Devices, Inc. [AMD] FCH USB EHCI Controller (rev 49)
00:14.0 SMBus: Advanced Micro Devices, Inc. [AMD] FCH SMBus Controller (rev 4b)
00:14.3 ISA bridge: Advanced Micro Devices, Inc. [AMD] FCH LPC Bridge (rev 11)
00:18.0 Host bridge: Advanced Micro Devices, Inc. [AMD] Stoney HT Configuration
00:18.1 Host bridge: Advanced Micro Devices, Inc. [AMD] Stoney Address Maps
00:18.2 Host bridge: Advanced Micro Devices, Inc. [AMD] Stoney DRAM Configuration
00:18.3 Host bridge: Advanced Micro Devices, Inc. [AMD] Stoney Miscellaneous Configuration
00:18.4 Host bridge: Advanced Micro Devices, Inc. [AMD] Stoney PM Configuration
00:18.5 Host bridge: Advanced Micro Devices, Inc. [AMD] Stoney NB Performance Monitor
01:00.0 Ethernet controller: Realtek Semiconductor Co., Ltd. RTL810xE PCI Express Fast Ethernet controller (rev 07)
02:00.0 Network controller: Realtek Semiconductor Co., Ltd. RTL8821CE 802.11ac PCIe Wireless Network Adapter

Answer 1

According to ethtool output it's a 100mbps card, therefore r8168 would be the wrong driver. Matching vendor driver is r8101. Better check whether firmware is loaded (if your chip version needs firmware). Helpful would be: dmesg | grep r8169