Have you verified the issue isn't a problem upstream in the network? Try plugging in a different device.
Linux
From Wikipedia, the free encyclopedia
Linux is a family of open source Unix-like operating systems based on the Linux kernel, an operating system kernel first released on September 17, 1991 by Linus Torvalds. Linux is typically packaged in a Linux distribution (or distro for short).
Distributions include the Linux kernel and supporting system software and libraries, many of which are provided by the GNU Project. Many Linux distributions use the word "Linux" in their name, but the Free Software Foundation uses the name GNU/Linux to emphasize the importance of GNU software, causing some controversy.
Rules
- Posts must be relevant to operating systems running the Linux kernel. GNU/Linux or otherwise.
- No misinformation
- No NSFW content
- No hate speech, bigotry, etc
Related Communities
Community icon by Alpár-Etele Méder, licensed under CC BY 3.0
I believe the installer version of Debian uses a newer kernel than the one it installs later, that's why your ethernet worked during installation. Sounds like a borked driver for the specific ethernet adapter and the older kernel. Get a usb-2-ethernet adapter, and retry to update the system, in case you get a newer kernel after updating it.
Proliant G9 is an EoL server that hasn't been sold since 2018. Meanwhile, Debian bookworm released last year. I'd be surprised if the problem were that your installer gave you a kernel that's too old.
What is the output of ip addr show
?