Temporary resolution error of "deb.debian.org".

Hello,

I just installed Debian Buster 10.4 on an HP Proliant server.
I had a tough time installing the network drivers, here's the topic I created: https://debian-facile.org/viewtopic.php?id=27754

My problem: I can't run apt update or upgrade (nor apt install for that matter), I get the error: Temporary name resolution error for "deb.debian.org".
I've checked my network settings, I switched from a static configuration to DHCP, no change. I tried an apt update && apt -y upgrade --fix-missing, nothing changed..

What’s really strange is that the error looks like a DNS config issue, yet I can ping www.google.com without any problem; I even tried the DNS address 8.8.8.8, with no result.

I feel like the problem is more related to my sources.list file; yet it is "new", I haven't touched it since installation, and it doesn't seem messed up (am I wrong?) :

# deb cdrom:[Debian GNU/Linux 10.4.0 _Buster_ - Official amd64 NETINST 20200509-10:25]/ buster main

#deb cdrom:[Debian GNU/Linux 10.4.0 _Buster_ - Official amd64 NETINST 20200509-10:25]/ buster main

deb http://deb.debian.org/debian/ buster main non-free contrib
deb-src http://deb.debian.org/debian/ buster main non-free contrib

deb http://security.debian.org/debian-security/ buster/updates main contrib non-free
deb-src http://security.debian.org/debian-security/ buster/updates main contrib non-free

# buster-updates, previously known as 'volatile'
deb http://deb.debian.org/debian/ buster-updates main contrib non-free
deb-src http://deb.debian.org/debian/ buster-updates main contrib non-free

# This system was installed using small removable media
# (e.g. netinst, live or single CD). The matching “deb cdrom”
# entries were disabled at the end of the installation process.
# For information about how to configure apt package sources,
# see the sources.list(5) manual.

Can you please help me resolve this issue?

EDIT: Seriously, what the hell is this :') I can ping debian.org but can't run apt?