При подключении ethernet кабеля ноль реакции. Network mananager молчит. Кабель исправен. В /etc/network/interfaces 3 строки
# interfaces(5) file used by ifup(8) and ifdown(8)
auto lo
iface lo inet loopback
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1
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: enp3s5: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc pfifo_fast state DOWN group default qlen 1000
link/ether 00:50:bf:5b:da:9a brd ff:ff:ff:ff:ff:ff
03:05.0 Ethernet controller: Realtek Semiconductor Co., Ltd. RTL-8100/8101L/8139 PCI Fast Ethernet Adapter (rev 10)
Subsystem: Realtek Semiconductor Co., Ltd. RTL-8100/8101L/8139 PCI Fast Ethernet Adapter
Kernel driver in use: 8139too
Kernel modules: 8139cp, 8139too
[ 2.469705] 8139too 0000:03:05.0 eth0: RealTek RTL8139 at 0x000000000001e800, 00:50:bf:5b:da:9a, IRQ 20
[ 2.503189] 8139too 0000:03:05.0 enp3s5: renamed from eth0
UPD: ethtool enp3s5
Settings for enp3s5:
Supported ports: [ TP MII ]
Supported link modes: 10baseT/Half 10baseT/Full
100baseT/Half 100baseT/Full
Supported pause frame use: No
Supports auto-negotiation: Yes
Advertised link modes: Not reported
Advertised pause frame use: No
Advertised auto-negotiation: No
Speed: 10Mb/s
Duplex: Full
Port: MII
PHYAD: 32
Transceiver: internal
Auto-negotiation: off
Cannot get wake-on-lan settings: Operation not permitted
Current message level: 0x00000007 (7)
drv probe link
Link detected: no