Dear Debian,
I just tried it again, and got the same result.
If you download the standard vanilla Debian netinstall ISO, create a VBox, and install, it works fine. I just confirmed this by downloading a fresh one. I know it's a new one because it includes the non-free-firmware part in the sources.list, which is new. A netinstall ISO from last week didn't mention firmware.
1st login, make user a member of sudo.
useradd mike sudo
Login as mike,
sudo pluma
as root, open & edit the /etc/apt/sources.list. Delete everything and add 2 lines ~
Save and close.
Now, as root or as mike,
sudo apt update ; sudo apt dist upgrade
Standard method of upgrading from vanilla to sid.
Problem is, it breaks your networking.
It loses your nic and any reference to it, any settings, any ip address ...
You cannot add something else because there is no network.
You cannot update or install anything. I sent a big email a couple of days ago, which covered how you might work around that, but so far, it has not been fixed.
By my reckoning, it's been 6 days now.
If my understanding is correct, then nobody anywhere can install a vanilla Debian and upgrade to sid while this problem remains.
Yes, I am aware there are other install ISOs, there's about 80 of them.
I did find one that is a daily build of Trixie, and that has no problems, although I didn't try to upgrade it to sid. I'm rather pleased to have a working Trixie and I don't want to break it.
One (very long & tedious) way around this, I mentioned in my previous email. It does work, but you might as well create a new Linux from Scratch. It's a lot of messing about to achieve something that should be quite straightforward.
There are something over a hundred sites and pages up, that give simple logical instructions about how you install Debian and upgrade to sid. Every one of those pages is currently wrong.
Yours respectfully,
Mike