WLAN funciona, a LAN não, determinados sites no navegador não conseguem se conectar, ping www.google.com connect: a rede está inacessível

Question

Meu sistema operacional é o Ubuntu 16.04. Eu acho que fiz algo errado no passado. Eu sempre usei WLAN para se conectar à internet e estava tudo bem. Hoje eu queria usar a LAN, mas não funciona corretamente.

Primeiro, para muitos sites no Firefox eu recebo: "Não é possível conectar-se". O Google funciona, mas muitos outros sites não (por exemplo, speedtest.net).

Em segundo lugar, no meu terminal, não consigo pingar nada. Por exemplo, ping www.google.com . Eu recebo connect: Network is unreachable

Mais uma vez, a WLAN funciona bem, mas a LAN não funciona.

ifconfig:

eth0      Link encap:Ethernet  HWaddr f0:de:f1:00:02:54  
          UP BROADCAST MULTICAST  MTU:1500  Metric:1
          RX packets:2420 errors:0 dropped:0 overruns:0 frame:0
          TX packets:1439 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:2686690 (2.6 MB)  TX bytes:207739 (207.7 KB)
          Interrupt:20 Memory:f2500000-f2520000 

lo        Link encap:Local Loopback  
          inet addr:127.0.0.1  Mask:255.0.0.0
          inet6 addr: ::1/128 Scope:Host
          UP LOOPBACK RUNNING  MTU:65536  Metric:1
          RX packets:1399 errors:0 dropped:0 overruns:0 frame:0
          TX packets:1399 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1 
          RX bytes:129446 (129.4 KB)  TX bytes:129446 (129.4 KB)

wlan0     Link encap:Ethernet  HWaddr 00:26:c7:54:99:0a  
          inet addr:192.168.178.40  Bcast:192.168.178.255  Mask:255.255.255.0
          inet6 addr: fe80::226:c7ff:fe54:990a/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:2370 errors:0 dropped:0 overruns:0 frame:0
          TX packets:2734 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:1117949 (1.1 MB)  TX bytes:433103 (433.1 KB)

ip a:

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: eth0: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc pfifo_fast state DOWN group default qlen 1000
    link/ether f0:de:f1:00:02:54 brd ff:ff:ff:ff:ff:ff
3: wlan0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state UP group default qlen 1000
    link/ether 00:26:c7:54:99:0a brd ff:ff:ff:ff:ff:ff
    inet 192.168.178.40/24 brd 192.168.178.255 scope global dynamic wlan0
       valid_lft 863788sec preferred_lft 863788sec
    inet6 fe80::226:c7ff:fe54:990a/64 scope link 
       valid_lft forever preferred_lft forever

rota ip:

10.0.0.0/24 dev eth0  proto kernel  scope link  src 10.0.0.1  metric 100

rota ip -6:

2a02:908:1473:3b20::/64 dev eth0  proto kernel  metric 256  expires 7111sec pref medium
2a02:908:1473:3b20::/59 via fe80::ca0e:14ff:fe91:4c8b dev eth0  proto ra  metric 100  pref medium
fe80::/64 dev eth0  proto kernel  metric 256  pref medium
default via fe80::ca0e:14ff:fe91:4c8b dev eth0  proto static  metric 100  pref medium 

ping6 www.google.com:

PING www.google.com(ams17s01-in-x04.1e100.net) 56 data bytes
64 bytes from ams17s01-in-x04.1e100.net: icmp_seq=1 ttl=51 time=35.1 ms
64 bytes from ams17s01-in-x04.1e100.net: icmp_seq=2 ttl=51 time=33.7 ms
64 bytes from ams17s01-in-x04.1e100.net: icmp_seq=3 ttl=51 time=24.9 ms