最終突破口->参照シャーク以下の結果はいくつかの手がかりを提供します。
こんにちは。家には次の設定があります。
インターネット - NAS（Ubuntu 16.04.4 LTS） - LAN（ASUS N56U WiFi） - 個人ユーザー。 NAS接続使用量PPPOE（ppp0、ケーブル）をインターネットに接続し、eth0（192.168.0.1、ケーブル）をLANに接続します。 ASUS N56U は固定 IP 192.168.0.2/255.255.255.0 および DNS 192.168.0.1 を使用して NAS に接続します。
すべてがうまくいきます。
NASとホームユーザーはインターネットにアクセスし、インターネットはNASにアクセスします。
私はAsus N56Uと交換したばかりの別の非常に似たルーター（Asus RT-AC66U）を持っています。同様に簡単な設定動作しません：（。私の言葉はどういう意味ですか？触れる私の個人的なウェブサイトはまだLAN経由でアクセスできますが、インターネットがダウンしています。
NAS（108.177.119.94はwww.google.ro）でこのコマンドを試しました。
sudo tcpdump -AX -vnni eth0 -c 2 dst 108.177.119.94
ルータで実行する場合（Telnet経由でアクセスできます）：
ping -c 2 108.177.119.94
N56U用にこれを得ました：
09:00:47.036839 IP (tos 0x0, ttl 64, id 0, offset 0, flags [DF], proto ICMP (1), length 84)
192.168.0.2 > 108.177.119.94: ICMP echo request, id 63814, seq 0, length 64
0x0000: 4500 0054 0000 4000 4001 95ef c0a8 0002 E..T..@.@.......
0x0010: 6cb1 775e 0800 d64a f946 0000 7cd9 ab94 l.w^...J.F..|...
0x0020: 0000 0000 0000 0000 0000 0000 0000 0000 ................
0x0030: 0000 0000 0000 0000 0000 0000 0000 0000 ................
0x0040: 0000 0000 0000 0000 0000 0000 0000 0000 ................
0x0050: 0000 0000 ....
09:00:48.044176 IP (tos 0x0, ttl 64, id 0, offset 0, flags [DF], proto ICMP (1), length 84)
192.168.0.2 > 108.177.119.94: ICMP echo request, id 63814, seq 1, length 64
0x0000: 4500 0054 0000 4000 4001 95ef c0a8 0002 E..T..@.@.......
0x0010: 6cb1 775e 0800 95eb f946 0001 ad37 bb94 l.w^.....F...7..
0x0020: 0000 0000 0000 0000 0000 0000 0000 0000 ................
0x0030: 0000 0000 0000 0000 0000 0000 0000 0000 ................
0x0040: 0000 0000 0000 0000 0000 0000 0000 0000 ................
0x0050: 0000 0000 ....
AC66U（問題のもの）の場合：
09:07:16.655875 IP (tos 0x0, ttl 64, id 0, offset 0, flags [DF], proto ICMP (1), length 84)
192.168.0.2 > 108.177.119.94: ICMP echo request, id 27906, seq 0, length 64
0x0000: 4500 0054 0000 4000 4001 95ef c0a8 0002 E..T..@.@.......
0x0010: 6cb1 775e 0800 638c 6d02 0000 de6b 4905 l.w^..c.m....kI.
0x0020: 0000 0000 0000 0000 0000 0000 0000 0000 ................
0x0030: 0000 0000 0000 0000 0000 0000 0000 0000 ................
0x0040: 0000 0000 0000 0000 0000 0000 0000 0000 ................
0x0050: 0000 0000 ....
09:07:17.668123 IP (tos 0x0, ttl 64, id 0, offset 0, flags [DF], proto ICMP (1), length 84)
192.168.0.2 > 108.177.119.94: ICMP echo request, id 27906, seq 1, length 64
0x0000: 4500 0054 0000 4000 4001 95ef c0a8 0002 E..T..@.@.......
0x0010: 6cb1 775e 0800 7e18 6d02 0001 b4de 5805 l.w^..~.m.....X.
0x0020: 0000 0000 0000 0000 0000 0000 0000 0000 ................
0x0030: 0000 0000 0000 0000 0000 0000 0000 0000 ................
0x0040: 0000 0000 0000 0000 0000 0000 0000 0000 ................
0x0050: 0000 0000 ....
N56Uを使用すると入手できます（使用TCPダンプ）要求はeth0からppp0を介してインターネットに送信され、AC66Uの場合は上記の結果が表示されます（要求はeth0で受信され、その後は何も受信されません）。
何が問題なのでしょうか？
編集4 （以下に考えられる問題を指摘します）
上記の結果（* .pcapファイルとして保存）を表示する別の方法は次のとおりです。シャーク(フレーム1のみ)
N56Uの場合は、次のようになります。
$tshark -r n56u-eth0-dst.pcap -V
Frame 1: 98 bytes on wire (784 bits), 98 bytes captured (784 bits)
Encapsulation type: Ethernet (1)
Arrival Time: May 5, 2018 09:00:47.036839000 EEST
[Time shift for this packet: 0.000000000 seconds]
Epoch Time: 1525500047.036839000 seconds
[Time delta from previous captured frame: 0.000000000 seconds]
[Time delta from previous displayed frame: 0.000000000 seconds]
[Time since reference or first frame: 0.000000000 seconds]
Frame Number: 1
Frame Length: 98 bytes (784 bits)
Capture Length: 98 bytes (784 bits)
[Frame is marked: False]
[Frame is ignored: False]
[Protocols in frame: eth:ethertype:ip:icmp:data]
Ethernet II, Src: Motorola_1b:ed:f2 (98:0c:a5:1b:ed:f2), Dst: AsrockIn_7c:28:bf (d0:50:99:7c:28:bf)
Destination: AsrockIn_7c:28:bf (d0:50:99:7c:28:bf)
Address: AsrockIn_7c:28:bf (d0:50:99:7c:28:bf)
.... ..0. .... .... .... .... = LG bit: Globally unique address (factory default)
.... ...0 .... .... .... .... = IG bit: Individual address (unicast)
Source: Motorola_1b:ed:f2 (98:0c:a5:1b:ed:f2)
Address: Motorola_1b:ed:f2 (98:0c:a5:1b:ed:f2)
.... ..0. .... .... .... .... = LG bit: Globally unique address (factory default)
.... ...0 .... .... .... .... = IG bit: Individual address (unicast)
Type: IPv4 (0x0800)
Internet Protocol Version 4, Src: 192.168.0.2, Dst: 108.177.119.94
0100 .... = Version: 4
.... 0101 = Header Length: 20 bytes (5)
Differentiated Services Field: 0x00 (DSCP: CS0, ECN: Not-ECT)
0000 00.. = Differentiated Services Codepoint: Default (0)
.... ..00 = Explicit Congestion Notification: Not ECN-Capable Transport (0)
Total Length: 84
Identification: 0x0000 (0)
Flags: 0x02 (Don't Fragment)
0... .... = Reserved bit: Not set
.1.. .... = Don't fragment: Set
..0. .... = More fragments: Not set
Fragment offset: 0
Time to live: 64
Protocol: ICMP (1)
Header checksum: 0x95ef [validation disabled]
[Header checksum status: Unverified]
Source: 192.168.0.2
Destination: 108.177.119.94
[Source GeoIP: Unknown]
[Destination GeoIP: United States, AS15169 Google Inc., Mountain View, CA, 37.419201, -122.057404]
[Destination GeoIP Country: United States]
[Destination GeoIP AS Number: AS15169 Google Inc.]
[Destination GeoIP City: Mountain View, CA]
[Destination GeoIP Latitude: 37.419201]
[Destination GeoIP Longitude: -122.057404]
Internet Control Message Protocol
Type: 8 (Echo (ping) request)
Code: 0
Checksum: 0xd64a [correct]
[Checksum Status: Good]
Identifier (BE): 63814 (0xf946)
Identifier (LE): 18169 (0x46f9)
Sequence number (BE): 0 (0x0000)
Sequence number (LE): 0 (0x0000)
Data (56 bytes)
0000 7c d9 ab 94 00 00 00 00 00 00 00 00 00 00 00 00 |...............
0010 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
0020 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
0030 00 00 00 00 00 00 00 00 ........
Data: 7cd9ab940000000000000000000000000000000000000000...
[Length: 56]
AC66Uの場合は、次のようになります。
$tshark -r ac66u-eth0-dst.pcap -V
Frame 1: 98 bytes on wire (784 bits), 98 bytes captured (784 bits)
Encapsulation type: Ethernet (1)
Arrival Time: May 5, 2018 09:07:16.655875000 EEST
[Time shift for this packet: 0.000000000 seconds]
Epoch Time: 1525500436.655875000 seconds
[Time delta from previous captured frame: 0.000000000 seconds]
[Time delta from previous displayed frame: 0.000000000 seconds]
[Time since reference or first frame: 0.000000000 seconds]
Frame Number: 1
Frame Length: 98 bytes (784 bits)
Capture Length: 98 bytes (784 bits)
[Frame is marked: False]
[Frame is ignored: False]
[Protocols in frame: eth:ethertype:ip:icmp:data]
Ethernet II, Src: AsustekC_cb:20:d0 (2c:56:dc:cb:20:d0), Dst: Broadcast (ff:ff:ff:ff:ff:ff)
Destination: Broadcast (ff:ff:ff:ff:ff:ff)
Address: Broadcast (ff:ff:ff:ff:ff:ff)
.... ..1. .... .... .... .... = LG bit: Locally administered address (this is NOT the factory default)
.... ...1 .... .... .... .... = IG bit: Group address (multicast/broadcast)
Source: AsustekC_cb:20:d0 (2c:56:dc:cb:20:d0)
Address: AsustekC_cb:20:d0 (2c:56:dc:cb:20:d0)
.... ..0. .... .... .... .... = LG bit: Globally unique address (factory default)
.... ...0 .... .... .... .... = IG bit: Individual address (unicast)
Type: IPv4 (0x0800)
Internet Protocol Version 4, Src: 192.168.0.2, Dst: 108.177.119.94
0100 .... = Version: 4
.... 0101 = Header Length: 20 bytes (5)
Differentiated Services Field: 0x00 (DSCP: CS0, ECN: Not-ECT)
0000 00.. = Differentiated Services Codepoint: Default (0)
.... ..00 = Explicit Congestion Notification: Not ECN-Capable Transport (0)
Total Length: 84
Identification: 0x0000 (0)
Flags: 0x02 (Don't Fragment)
0... .... = Reserved bit: Not set
.1.. .... = Don't fragment: Set
..0. .... = More fragments: Not set
Fragment offset: 0
Time to live: 64
Protocol: ICMP (1)
Header checksum: 0x95ef [validation disabled]
[Header checksum status: Unverified]
Source: 192.168.0.2
Destination: 108.177.119.94
[Source GeoIP: Unknown]
[Destination GeoIP: United States, AS15169 Google Inc., Mountain View, CA, 37.419201, -122.057404]
[Destination GeoIP Country: United States]
[Destination GeoIP AS Number: AS15169 Google Inc.]
[Destination GeoIP City: Mountain View, CA]
[Destination GeoIP Latitude: 37.419201]
[Destination GeoIP Longitude: -122.057404]
Internet Control Message Protocol
Type: 8 (Echo (ping) request)
Code: 0
Checksum: 0x638c [correct]
[Checksum Status: Good]
Identifier (BE): 27906 (0x6d02)
Identifier (LE): 621 (0x026d)
Sequence number (BE): 0 (0x0000)
Sequence number (LE): 0 (0x0000)
Data (56 bytes)
0000 de 6b 49 05 00 00 00 00 00 00 00 00 00 00 00 00 .kI.............
0010 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
0020 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
0030 00 00 00 00 00 00 00 00 ........
Data: de6b49050000000000000000000000000000000000000000...
[Length: 56]
私の考えにはこの部分ではないかと思います（AC66Uの場合）。
Destination: Broadcast (ff:ff:ff:ff:ff:ff)
何かが間違っているという意味ですか？どんな手がかりがありますか？