How to use wired connection?

I have a wired connection now, and both NetBSD and FreeBSD work well except OpenBSD, which file should I edit?

What/where's the dmesg?

Without any relevant information:
⇒ See:

CiotBSD
see termbin
I use ifconfig rtwn0 up and then connected to internet, but only succeed once.

this is my ifconfig output termbin
I use these commands and connected to the internet

ifconfig re0 up
ifconfig re0 inet autoconf

reference here

On OpenBSD (7.3) I have this file for wired: /etc/hostname.em0

and it contains this one line:

inet autoconf

If your router supports ip6 maybe add this second line:

inet6 autoconf

That works fine for an old router I used for wired (long story on why that router).