Try installing systemd-resolved
https://www.debian.org/releases/bookworm/amd64/release-notes/ch-information.en.html#systemd-resolved
seems like Debian split it into a seperate package
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Kinda strange that it's not installed by default. Maybe the VPS runs dnsmasq, OP maybe check that before installing.
Maybe it's not in the $PATH? I remember having similar problems a while ago.
You could search for it find / -name resolvectl
(might take a while when searching in /
), and check if the path is present in the $PATH variable.
the command doesn't output anything.
I just saw that there seems to be a separate package for systemd-resolved on Debian (https://packages.debian.org/search?searchon=contents&keywords=resolvectl&mode=exactfilename&suite=bookworm&arch=any), maybe check if the package systemd-resolved is actually installed.
Then it really does not exist, strange.
Maybe check where the systemd binaries are located and check if something's there, for example which systemctl
and look in that directory