how to determine network device names

[hput]

ubuntu 21.04    
I read that one can determine the possible name of a network device by
using 'lspci'

https://askubuntu.com/questions/1060052/how-to-find-out-which-interface-name-to-use
(under: `How to find out which interface name to use?')

>From about 3.5 yrs ago.

The comments I read did not give a forumula of what to extract from
the numerals proceeding the rest of the line but showed some examples.

So using the output lspci below

   [...]
   03:00.0  Ethernet controller Realtek semiconductor [...]
   [...]

It seems like I should be able to piece together an enpxxx type device
name by extrapolating from those examples:

I came up with `enp3s0' but of course when I try that with ifconfig.

  ifconfig enp3s0

I just get `error fetching interface information ... device not found'


Since the host I'm trying to create a network on has no network making
bit more difficult to capture actual output

Before I go any further I hoped someone would be kind enough to tell
me I'm way off the mark or whatever.

Maybe suggesting some better way to proceed.

I can tell you that booting with an ethernet cable connected to a  wifi
router with ethernet ports does nothing toward getting a network up.

The network icon on systray seems to be all about wifi

I'm running with ubuntu but with an lxde desktop so might be different
if it was straight ubuntu ... I don't know.