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I have this Ubuntu Server 18.04 LTS running and recently I changed my router subnet to 10.10.1.X. Also, I set DHCP to assign from 10.10.1.105 - 10.10.1.253 to other devices, since I want 100,101,102 and 103 for static purposes.

So, since in Ubuntu 18.04 netplan is now used, I have it set accordingly:

network:
  version: 2
  renderer: networkd
  ethernets:
    enp0s20:
      dhcp4: no
      dhcp6: no
      addresses: [10.10.1.100/24]
      gateway4: 10.10.1.1
      nameservers:
        addresses: [8.8.8.8,8.8.4.4]

I generate the configurations and run apply and it works for a while. Then, it stops probing websites: I can still use it on lan, but can no longer curl or nslookup. However, my Plex Server always works, since it accepts external connections.

After apply, netstat -r shows the correct routes but when it stops probing, they all disappear!

Edit: I have also disabled IPV6 a while ago, to implement a kill switch. But the kill switch is off right now

Edit 2: Just reset everything. Re-enabled IPv6 and used the same configuration file as before but with 8.8.8.8 and 1.1.1.1 as dns servers and removed the dhcp6: no. After rebooting it was working and then stops working

Edit 3: Removing nameservers I get this message

nslookup google.com
Server:     127.0.0.53
Address:    127.0.0.53#53

** server can't find google.com: SERVFAIL

When I readd nameservers, it work for a while, thens stops working, and eventually it works again. Am I being blocked by nameservers??

  • What do you mean "probing websites"? – heynnema Jun 9 at 0:27
  • Ping, telnet, nslookup, etc. Cannot connect – 12tst321 Jun 9 at 0:30
  • ps: I do a similar thing with my dhcp... only I place static IPs to <.100, and set the dhcp pool to .100-.253. This way my systemic devices are at a known IP range, and anything .100 or over is via dhcp. – heynnema Jun 9 at 0:30
  • Can you ping 8.8.8.8, and not ping www.ebay.com? – heynnema Jun 9 at 0:30
  • I can ping the former and not ping the latter, i suspect it is DNS problem. However, I have just cleared everything, dhcp4=yes and made the ip static on router. And I can only ping IPs, not names. Router should handle the DNS now – 12tst321 Jun 9 at 8:20

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