Unfortunately, the former is not possible due to asinine requirements by the HDMI Forum: https://www.phoronix.com/news/HDMI-2.1-OSS-Rejected The only option is to use DisplayPort instead (or perhaps an adapter).
I've created a small helper script to help me with this:
#!/bin/bash
USED_VER=$(uname -r)
echo "Kernel version in use: $USED_VER"
echo "Other installed versions:"
dpkg --list 'linux-image*' | grep ^ii | grep -v $USED_VER
echo "Remove unneeded packages above using the following command:"
echo "sudo apt remove linux-image-VERSION"
It prints a list of the installed kernels (excl. the running one) and prints the command to uninstall the packages (it doesn't remove anything by itself).
That sounds pretty bad and probably means other things are broken too. The easiest option would probably be a reinstall at this point, but if you want to learn something you can also try to salvage your install.
To recover, it's probably easiest to manually configure your Ethernet connection as described by InnerScientist and then re-install the network-manager package.
You can check the status of the network-manager package using dpgk. It should look like this (ii at the start, but it sounds like it's not installed in your case):
$ dpkg -l | grep -i network-manager
ii network-manager 1.52.1-1 amd64 network management framework (daemon and userspace tools)
ii network-manager-l10n 1.52.1-1 all network management framework (translation files)
You can also check /var/log/apt/history.log to see what went wrong and if there are other things you need to fix.
I performed the upgrade in two steps apt upgrade --without-new-pkgs and apt full-upgrade (based on the release notes). I can see the following on the line Upgrade: for the command apt full-upgrade:
network-manager:amd64 (1.42.4-1+deb12u1, 1.52.1-1)
On the Remove: line you can see the packages that were removed. Unfortunately, the names of many libraries were changed in this release (e.g., libreadline8:amd64 to libreadline8t64:amd64), so there's a lot of noise in there. Maybe you can look at that line and ignore everything that starts with lib to see if any other important packages were removed.
One thing that comes to mind is that the 50series is only supperted by the open version of the proprietary Nvidia drivers. The closed version doesn't support your new GPU, but would work with your old GPU. Do you know which version you installed?
Plasma 6 is a significant upgrade for sure, especially on Wayland! I'd rate the crash frequency (on Fedora) at between once per week and once per month ;-)
Your changes can't hurt me!
I'm running Ubuntu on a server. I've enabled the free Ubuntu Pro subscription to get ESM patches for the universe repository. Not sure if it really matters, but better safe than sorry.
The easiest distros to run Resolve would probably be Rocky Linux 8, Alma Linux 8 (both are based on RHEL 8). Instead of the EOL Rocky/Alma 8.6, you should use release 8.10 (8.6 would update to 8.10 anyway). However, while still currently "supported", these are still shipping (mostly) 6-year-old (!) packages. Also, only a small number of packages is actively supported by Red Hat. IMO, this implies that these distros offer a lower level of security. The most critical parts (browser, kernel) are still well-supported, so the difference is probably not too large for most regular users. However, you may also struggle to run some other software (although Flatpaks are available). It's unfortunate that Resolve only supports an ancient version of Rocky (Rocky 10 is now out)...
Read (only) access should be fine. What makes it complicated is if there can be writes from multiple locations. Basically, the simple version would be to just periodically copy the data from the primary to all secondary locations.
I can see why you'd want to go with an off-the-shelf NAS. But, I would carefully check if it supports your use case, as it's quite advanced.
If the data only needs to be read & written from a single server (and the others are just backups), you can also use simpler replication instead of synchthing. E.g. syncoid or TrueNAS replication. It sounds like you should be able to do that with separate datasets per household in your usecase.
No, Debian is typically quite a bit older than even the Ubuntu LTS. E.g. they currently still don't ship a Nvidia driver that supports the 50 series GPUs.