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Good evening,

We have 15-20 devices running on our office LAN. Suddenly last week, the internet (both wired and wireless) suddenly cut-off on both of 2 Mint desktops. By cut-off i mean that the wifi connection status is OK but all requests to the internet result in a timeout

In further troubleshooting, I realized that:

  • Windows devices work

  • Windows works on one of the Mint devices with dual boot

  • Android devices work

  • Both devices work on external networks (ie coffeeshop)

  • The devices can ping 4.2.2.2 from inside the LAN

  • The devices can ping the public ip of our AP

  • The devices have an IP address (ifconfig) which can be pinged by other devices. It can also ping devices within the network

  • Unplugging the router for 15s does not help

  • The router (AN5506-04) will not factory reset as per instructions found on the net (press sunken button with a pin)

  • LiveUSB of Mint18 and Ubuntu16.04 both don't work

  • Chromium hangs on 'Resolving Host' and throws an error dns_probe_finished_bad_config

I don't think that there was a software update when it cut.

I believe this is something to do with DHCP within the LAN or the DNS of my ISP but I'm not sure where to begin on troubleshooting. Does anyone have some tips on what I might try next to get this back up and running?

===================

ifconfig and routes for Windows and Mint on the dual boot device (inside LAN)


Windows (Works fine)

IPv4 Route Table 

======================================================================= 

Active Routes:      

Network Destination        Netmask          Gateway       Interface  Metric                                                       

0.0.0.0          0.0.0.0      192.168.1.1     192.168.1.10     50 

127.0.0.0        255.0.0.0         On-link         127.0.0.1    331                                                     

127.0.0.1  255.255.255.255         On-link         127.0.0.1    331                                               

127.255.255.255  255.255.255.255         On-link         127.0.0.1    331                                                   

192.168.1.0    255.255.255.0         On-link      192.168.1.10    306                                                  

192.168.1.10  255.255.255.255         On-link      192.168.1.10    306                                                 

192.168.1.255  255.255.255.255         On-link      192.168.1.10    306                                                     

224.0.0.0        240.0.0.0         On-link         127.0.0.1    331                                                     

224.0.0.0        240.0.0.0         On-link      192.168.1.10    306                                               

255.255.255.255  255.255.255.255         On-link         127.0.0.1    331                                               

255.255.255.255  255.255.255.255         On-link      192.168.1.10    306                                             

=====================================================================
Persistent Routes:
None            

result of ipconfig

Windows IP Configuration

Ethernet adapter Ethernet:

   Connection-specific DNS Suffix  . :

   Link-local IPv6 Address . . . . . : fe80::6c87:d693:d07c:f401%3

   IPv4 Address. . . . . . . . . . . : 7.19.111.114

   Subnet Mask . . . . . . . . . . . : 255.255.192.0

   Default Gateway . . . . . . . . . : 7.19.64.1

Wireless LAN adapter Local Area Connection* 2:

   Media State . . . . . . . . . . . : Media disconnected

   Connection-specific DNS Suffix  . :

Ethernet adapter Ethernet 3:

   Media State . . . . . . . . . . . : Media disconnected

   Connection-specific DNS Suffix  . :

Wireless LAN adapter Wi-Fi:

   Connection-specific DNS Suffix  . : local

   Link-local IPv6 Address . . . . . : fe80::5d0a:4218:85a3:a0d3%14

   IPv4 Address. . . . . . . . . . . : 192.168.1.10

   Subnet Mask . . . . . . . . . . . : 255.255.255.0

   Default Gateway . . . . . . . . . : 192.168.1.1

Ethernet adapter Bluetooth Network Connection:

   Media State . . . . . . . . . . . : Media disconnected

   Connection-specific DNS Suffix  . :

Tunnel adapter Local Area Connection* 12:

   Connection-specific DNS Suffix  . :

   IPv6 Address. . . . . . . . . . . : 2001:0:4137:9e76:28a8:29fd:3f57:fef5

   Link-local IPv6 Address . . . . . : fe80::28a8:29fd:3f57:fef5%2

   Default Gateway . . . . . . . . . : ::

Mint 18.3 (Connected to LAN but all internet requests from browser timeout)

result of ip route

      default via 192.168.1.1 dev wlp2s0  proto static  metric 600 

      169.254.0.0/16 dev wlp2s0  scope link  metric 1000 

      192.168.1.0/24 dev wlp2s0  proto kernel  scope link  src 192.168.1.16  metric 600 

result of ifconfig

enp1s0 Link encap:Ethernet HWaddr 1c:39:47:1f:0d:4e

      inet addr:7.19.111.114  Bcast:7.19.127.255  Mask:255.255.192.0

      inet6 addr: fe80::e04:a1fc:1928:6173/64 Scope:Link

      UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1

      RX packets:41 errors:0 dropped:0 overruns:0 frame:0

      TX packets:40 errors:0 dropped:0 overruns:0 carrier:0

      collisions:0 txqueuelen:1000 

      RX bytes:4350 (4.3 KB)  TX bytes:6515 (6.5 KB)

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:302 errors:0 dropped:0 overruns:0 frame:0

      TX packets:302 errors:0 dropped:0 overruns:0 carrier:0

      collisions:0 txqueuelen:1000 

      RX bytes:21794 (21.7 KB)  TX bytes:21794 (21.7 KB)

wlp2s0

      Link encap:Ethernet  HWaddr 30:52:cb:60:c4:97  

      inet addr:192.168.1.4  Bcast:192.168.1.255  Mask:255.255.255.0

      inet6 addr: fe80::95ba:f296:18e7:ec8c/64 Scope:Link

      UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1

      RX packets:164 errors:0 dropped:0 overruns:0 frame:0

      TX packets:248 errors:0 dropped:0 overruns:0 carrier:0

      collisions:0 txqueuelen:1000 

      RX bytes:20760 (20.7 KB)  TX bytes:27802 (27.8 KB)

result of: sudo ethtool -i enp1s0

driver: r8169

version: 2.3LK-NAPI

firmware-version: rtl8168h-2_0.0.2 02/26/15

expansion-rom-version: 

bus-info: 0000:01:00.0

supports-statistics: yes

supports-test: no

supports-eeprom-access: no

supports-register-dump: yes

supports-priv-flags: no

sudo ethtool -i wlp2s0

driver: ath10k_pci

version: 4.10.0-38-generic

firmware-version: WLAN.TF.1.0-00267-1

expansion-rom-version: 

bus-info: 0000:02:00.0

supports-statistics: yes

supports-test: no

supports-eeprom-access: no

supports-register-dump: no

supports-priv-flags: no

sudo iw dev wlp2s0 link

Connected to *MAC address of Router AP* (on wlp2s0)

    SSID: *CorrectWifiNetwork*

    freq: 2432

    RX: 60228 bytes (439 packets)

    TX: 8743 bytes (67 packets)

    signal: -39 dBm

    tx bitrate: 1.0 MBit/s

    bss flags:  short-slot-time

    dtim period:    1

    beacon int: 100

nmcli device show wlp2s0 | grep IP4.DNS

IP4.DNS[1]: 192.168.1.1 *the local router and AP*
  • 1
    Post the actual error messages of your tests. Post the network configuration of the machines when they don't work, and the configuration of one that does work. – Gerald Schneider Sep 20 '18 at 13:41
  • All devices are connected via wifi. As far as I know, the only DHCP is on the main access point/router. There are no errors to speak of in the above. Just timeouts. Sorry, I'm not sure which configuration you are referring to. – graial Sep 20 '18 at 14:20
  • 1
    I was referring to the IP configuration, routing tables, proxy configuration if used. What addresses you tried to reach and with which protocols. – Gerald Schneider Sep 20 '18 at 14:34
  • On the dual boot unit, for example. If I post the result of ifconfig & ip route from Mint , followed by ipconfig & route print on Windows, both from inside the LAN will that help? There is no Proxy. Using a web browser, I have not yet found a website that successfully loads and the package manager cannot update. – graial Sep 20 '18 at 14:55
  • added outputs from ifconfig and ip route for both windows and mint from the same dual boot machine – graial Sep 20 '18 at 16:04
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As of today, I still believe this is an outage of my ISP's DNS servers

I found that adding a public DNS to a single device (including a LiveUSB/fresh install) using resolvconf allows me to get name-resolution back. I used directions from this post: https://unix.stackexchange.com/questions/128220/how-do-i-set-my-dns-when-resolv-conf-is-being-overwritten/163506#163506

Unfortunately, I believe this is a poor solution since I need to apply this fix to each Ubuntu/Mint device on the LAN individually. As a longer-term solution, I'm planning to install a second router with a server between my LAN and the locked-down router/AP provided by my ISP.

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