LAN reconfig on Ubuntu Server post install

[Ethan Evans]

So in August I set up a basic Ubuntu server on a spare-parts PC because I
wanted to run a Plex Media Server as a little project. However, being my
spare-parts PC, it had a Haswell i5 in it that I thought was more than
necessary for its task. I had also promised my brother my spare parts for
an entry-level gaming rig once he settled into his own apartment. My older
brother has just settled into an apartment (after being away for a few
months to do training for work) and in preparation to hand over my
spare-parts PC, I replaced the motherboard in the Plex server with an
ASRock J3355M embedded-CPU motherboard. The CPU is not powerful, but is
very power-efficient and I only use Plex for music streaming, so I believed
it would be powerful enough for what I use it for. But now the system will
not/cannot connect to the internet.

When I first installed and setup the server, I gave it a static IP address
on the LAN and setup port-forwarding to it. But our home network has a
dynamic IP address, so as long as I logged into the plex.tv website, I
could get the IP address of the home network and SSH into the server. After
installing the new motherboard, I booted the server and discovered the Plex
app on my phone could not find the server. I then began trying to
trouble-shoot on the server itself. I first tried to ping 1.1.1.1 and
8.8.8.8 (DNS servers) and those failed completely with the message:
"connect: Network is unreachable." I then tried to ping 192.168.0.1 (the
LAN router IP address) and it failed with the same results. Using the
command ifconfig, I get the following (partial results): "inet 127.0.0.1
netmask: 255.0.0.0" I think expected results would've been something like:
"inet 192.168.0.xxx netmask: 255.255.255.0" My guess is that the new LAN
chipset or whatever on the new MoBo has reset the LAN settings for the
server, but now I don't know how to set them again or if I might need to
try and install different drivers for it to work. Short of reinstalling the
entire Server OS, I don't know what to do. I could do that, but I'm hoping
it's unnecessary and am asking for your help.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://lists.ubuntu.com/archives/ubuntu-users/attachments/20181216/21ba4c9f/attachment.html>