Wired network keeps disconnecting for a few seconds at a time

Every few minutes or so the connection to the network completely drops for several seconds. I can see this in nload when there is no incoming or outgoing data for a few seconds even while running something like a Minecraft server for a constant network load. I know it is not the network because all of my other computers work fine even when this computer disconnects.

Here is the output of lspci:

02:00.0 Ethernet controller: Realtek Semiconductor Co., Ltd. RTL8111/8168/8411 PCI Express Gigabit Ethernet Controller (rev 0c)

I have tried installing the r8168 drivers, but those didn't seem to help, I also have tried reinstalling network manager and setting managed to true in the config but no luck.

I can see the connection and use it for a few minutes, it just disconnects for a few seconds and then reconnects like nothing happened, causing any network services to lag or time out. I am currently running Ubuntu 21.04 but this issue happened on 20.04 and 20.10 as well.

Edit:

lspci -nn | grep -i ethernet

02:00.0 Ethernet controller [0200]: Realtek Semiconductor Co., Ltd. RTL8111/8168/8411 PCI Express Gigabit Ethernet Controller [10ec:8168] (rev 0c)

sudo lshw -C network

*-network
       description: Ethernet interface
       product: RTL8111/8168/8411 PCI Express Gigabit Ethernet Controller
       vendor: Realtek Semiconductor Co., Ltd.
       physical id: 0
       bus info: pci@0000:02:00.0
       logical name: enp2s0
       version: 0c
       serial: 20:12:9d:20:02:6e
       size: 100Mbit/s
       capacity: 1Gbit/s
       width: 64 bits
       clock: 33MHz
       capabilities: pm msi pciexpress msix vpd bus_master cap_list ethernet physical tp mii 10bt 10bt-fd 100bt 100bt-fd 1000bt-fd autonegotiation
       configuration: autonegotiation=on broadcast=yes driver=r8169 driverversion=5.11.0-18-generic duplex=full firmware=rtl8168g-2_0.0.1 02/06/13 ip=192.168.0.240 latency=0 link=yes multicast=yes port=twisted pair speed=100Mbit/s
       resources: irq:18 ioport:e800(size=256) memory:fbdff000-fbdfffff memory:f8ffc000-f8ffffff

ip a | grep mtu

1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
2: enp2s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP group default qlen 1000

Logs for an instance of this happening

Jun 14 21:31:16 server NetworkManager[810]: <info>  [1623724276.7620] device (enp2s0): state change: activated -> unavailable (reason 'carrier-changed', sys-iface-state: 'managed')
Jun 14 21:31:16 server NetworkManager[810]: <info>  [1623724276.7770] dhcp4 (enp2s0): canceled DHCP transaction
Jun 14 21:31:16 server NetworkManager[810]: <info>  [1623724276.7770] dhcp4 (enp2s0): state changed bound -> done
Jun 14 21:31:16 server NetworkManager[810]: <info>  [1623724276.7970] manager: NetworkManager state is now DISCONNECTED
Jun 14 21:31:17 server NetworkManager[810]: <info>  [1623724277.1803] device (enp2s0): carrier: link connected
Jun 14 21:31:17 server NetworkManager[810]: <info>  [1623724277.1806] device (enp2s0): state change: unavailable -> disconnected (reason 'carrier-changed', sys-iface-state: 'managed')
Jun 14 21:31:17 server NetworkManager[810]: <info>  [1623724277.1815] policy: auto-activating connection 'netplan-enp2s0' (7ea6f90b-3495-3533-948a-ef0035687c34)
Jun 14 21:31:17 server NetworkManager[810]: <info>  [1623724277.1821] device (enp2s0): Activation: starting connection 'netplan-enp2s0' (7ea6f90b-3495-3533-948a-ef0035687c34)
Jun 14 21:31:17 server NetworkManager[810]: <info>  [1623724277.1823] device (enp2s0): state change: disconnected -> prepare (reason 'none', sys-iface-state: 'managed')
Jun 14 21:31:17 server NetworkManager[810]: <info>  [1623724277.1828] manager: NetworkManager state is now CONNECTING
Jun 14 21:31:17 server NetworkManager[810]: <info>  [1623724277.1830] device (enp2s0): state change: prepare -> config (reason 'none', sys-iface-state: 'managed')
Jun 14 21:31:17 server NetworkManager[810]: <info>  [1623724277.1836] device (enp2s0): state change: config -> ip-config (reason 'none', sys-iface-state: 'managed')
Jun 14 21:31:17 server NetworkManager[810]: <info>  [1623724277.1840] dhcp4 (enp2s0): activation: beginning transaction (timeout in 45 seconds)
Jun 14 21:31:19 server NetworkManager[810]: <info>  [1623724279.1925] dhcp4 (enp2s0): state changed unknown -> bound, address=192.168.0.240
Jun 14 21:31:19 server NetworkManager[810]: <info>  [1623724279.1943] device (enp2s0): state change: ip-config -> ip-check (reason 'none', sys-iface-state: 'managed')
Jun 14 21:31:19 server NetworkManager[810]: <info>  [1623724279.1985] device (enp2s0): state change: ip-check -> secondaries (reason 'none', sys-iface-state: 'managed')
Jun 14 21:31:19 server NetworkManager[810]: <info>  [1623724279.1989] device (enp2s0): state change: secondaries -> activated (reason 'none', sys-iface-state: 'managed')
Jun 14 21:31:19 server NetworkManager[810]: <info>  [1623724279.1996] manager: NetworkManager state is now CONNECTED_LOCAL
Jun 14 21:31:19 server NetworkManager[810]: <info>  [1623724279.2017] manager: NetworkManager state is now CONNECTED_SITE
Jun 14 21:31:19 server NetworkManager[810]: <info>  [1623724279.2019] policy: set 'netplan-enp2s0' (enp2s0) as default for IPv4 routing and DNS
Jun 14 21:31:19 server NetworkManager[810]: <info>  [1623724279.2023] policy: set 'netplan-enp2s0' (enp2s0) as default for IPv6 routing and DNS
Jun 14 21:31:19 server NetworkManager[810]: <info>  [1623724279.2031] device (enp2s0): Activation: successful, device activated.
Jun 14 21:31:19 server NetworkManager[810]: <info>  [1623724279.2041] manager: NetworkManager state is now CONNECTED_GLOBAL

Seems like "carrier changed" is causing this, I will look into that.

Hóa ra đó là cáp ethernet của tôi. Tôi không chắc tại sao nhưng nó đã gây ra những sự cố ngắt kết nối này, tôi đã đổi nó để lấy một cáp cat6 mới và kể từ đó tôi không gặp phải bất kỳ sự chậm trễ/mất kết nối nào.