Localhost doesn't work if I connect to internet via USB-C Ethernet Adapter

General system Newbie
1

Hello guys,

I have issue related to localhost. It can’t be resolved when I am connected via USB-C ethernet adapter to internet. If just adapter is plugged in, without cable, it works.

Any ideas what might cause the problem?

Thank you.

2

What are you using to resolve it?

Possibly related to systemd-resolved.

3

So pinging localhost shows you what?

How about

cat /etc/hosts
4

Ping, browsers or even nbfc says it is not able to recognize it.

ping: localhost: Name or service not known

hosts contains:

127.0.0.1       localhost
127.0.1.1       ebiroud
::1     localhost ip6-localhost ip6-loopback
ff02::1 ip6-allnodes
ff02::2 ip6-allrouters

Anyway, I noticed I’ve set Automatic (only addresses) in IPv4 settings in Network Manager to use custom DNSes only, not the ones that come with DHCP. If I set it to Automatic, localhost is pingable, works like a charm.

Weird is (at least for me) that with internal ethernet it doesn’t matter, could be set to Automatic (only addresses) and localhost would be still pingable.

5

Nor hostname, can’t be pinged as well, it just doesn’t recognize it.

6

Compare your /etc/resolv.conf before and after connecting to the network.

7

Before connecting to internet, it is empty, after connecting, DNS servers are written there.

Anyway, I tried to removing /etc/hosts /etc/nsswitch.conf, /etc/host.conf and reinstalling “filesystem”, reconfigure, without any clue why, it is working again.

Thank you for your effort!