I installed Debian on a (legacy) Optiplex 9010 desktop, using a minimal USB installation image, and netinst. IOW, most of the contents of this installation came in through the network (which rules out the most serious hardware issues).
One day later, the network connection suddenly stopped working, at all. For example, the response to `ping 8.8.8.8` is now `connect: Network is unreachable`. The problem is with the computer not with the jack, because if I plug a different computer to the same jack the connection works fine. I did not touch any network-related config files, so I can't begin to guess what could have caused this sudden failure. If I run `/etc/init.d/networking restart`, the output just says `Restarting networking (via systemctl): networking.service`. At the end of this message I post the relevant lines from the output I get if I then run `journalctl -xe` immediately after. One can see that the restart of the network is failing due to an ntpd problem. If I attempt to restart ntpd, I get the error "Failed to start ntpd.service: Unit nptd.service not found." This makes no sense to me: ntpd was clearly available and working for several hours before this sudden failure. The package is definitely installed, and the error above persists even after I run `dpkg-reconfigure -p low ntp` (which requires no input from me). The only fix I can think of at this point would be to reinstall ntp altogether, but I can't do this without an internet connection, so I have a Catch-22 situation. How can I fix this problem without having an internet connection? --- Aug 17 10:00:42 myhost ntpd[757]: error resolving pool 3.debian.pool.ntp.org: Temporary failure in name resolution (-3) Aug 17 10:00:45 myhost systemd[1]: Stopping Raise network interfaces... -- Subject: Unit networking.service has begun shutting down -- Defined-By: systemd -- Support: https://www.debian.org/support -- -- Unit networking.service has begun shutting down. Aug 17 10:00:46 myhost systemd[1]: Stopped Raise network interfaces. -- Subject: Unit networking.service has finished shutting down -- Defined-By: systemd -- Support: https://www.debian.org/support -- -- Unit networking.service has finished shutting down. Aug 17 10:00:46 myhost systemd[1]: Starting Raise network interfaces... -- Subject: Unit networking.service has begun start-up -- Defined-By: systemd -- Support: https://www.debian.org/support -- -- Unit networking.service has begun starting up. Aug 17 10:00:46 myhost systemd[1]: Started Raise network interfaces. -- Subject: Unit networking.service has finished start-up -- Defined-By: systemd -- Support: https://www.debian.org/support -- -- Unit networking.service has finished starting up. -- -- The start-up result is done. Aug 17 10:00:48 myhost ntpd[757]: error resolving pool 2.debian.pool.ntp.org: Temporary failure in name resolution (-3) Aug 17 10:00:49 myhost ntpd[757]: error resolving pool 1.debian.pool.ntp.org: Temporary failure in name resolution (-3)