First I'm going to recommend checking the resolved service is running
sudo systemctl status systemd-resolved
Ok, so I was able to replicate the output that you got when running nmap
nmap -A 192.168.68.118
Starting Nmap 7.94SVN ( https://nmap.org ) at 2025-09-27 10:01 NZST
mass_dns: warning: Unable to open /etc/resolv.conf. Try using --system-dns or specify valid servers with --dns-servers: No such file or directory (2)
mass_dns: warning: Unable to determine any DNS servers. Reverse DNS is disabled. Try using --system-dns or specify valid servers with --dns-servers
Nmap scan report for 192.168.68.118
Host is up (0.00014s latency).
Not shown: 999 closed tcp ports (conn-refused)
PORT STATE SERVICE VERSION
22/tcp open ssh OpenSSH 9.6p1 Ubuntu 3ubuntu13.14 (Ubuntu Linux; protocol 2.0)
| ssh-hostkey:
| 256 52:c4:1e:1a:e1:61:ed:16:55:7d:4d:4f:24:bf:9d:c6 (ECDSA)
|_ 256 ae:5c:cb:7f:0e:af:e4:38:b7:a9:b7:38:f2:e1:76:e9 (ED25519)
Service Info: OS: Linux; CPE: cpe:/o:linux:linux_kernel
Service detection performed. Please report any incorrect results at https://nmap.org/submit/ .
Nmap done: 1 IP address (1 host up) scanned in 0.37 seconds
I managed to do this by running:
sudo rm /etc/resolv.conf
However restarting fixed this, so to make it permanant I had to
sudo mv /run/systemd/resolve/stub-resolv.conf /run/systemd/resolve/stub-resolv.conf.bak
sudo rm /etc/resolv.conf
as /run/systemd/resolve/stub-resolv.conf is what /etc/resolv.conf is symbolically linked to.
The contents of /run/systemd/resolve/stub-resolv.conf is
# This is /run/systemd/resolve/stub-resolv.conf managed by man:systemd-resolved(8).
# Do not edit.
#
# This file might be symlinked as /etc/resolv.conf. If you're looking at
# /etc/resolv.conf and seeing this text, you have followed the symlink.
#
# This is a dynamic resolv.conf file for connecting local clients to the
# internal DNS stub resolver of systemd-resolved. This file lists all
# configured search domains.
#
# Run "resolvectl status" to see details about the uplink DNS servers
# currently in use.
#
# Third party programs should typically not access this file directly, but only
# through the symlink at /etc/resolv.conf. To manage man:resolv.conf(5) in a
# different way, replace this symlink by a static file or a different symlink.
#
# See man:systemd-resolved.service(8) for details about the supported modes of
# operation for /etc/resolv.conf.
nameserver 127.0.0.53
options edns0 trust-ad
search .
Which is a relativly fresh install of Ubuntu Server as a VM. And this is what it looks like on my main server with the adguard home bind fix enabled
# This is /run/systemd/resolve/resolv.conf managed by man:systemd-resolved(8).
# Do not edit.
#
# This file might be symlinked as /etc/resolv.conf. If you're looking at
# /etc/resolv.conf and seeing this text, you have followed the symlink.
#
# This is a dynamic resolv.conf file for connecting local clients directly to
# all known uplink DNS servers. This file lists all configured search domains.
#
# Third party programs should typically not access this file directly, but only
# through the symlink at /etc/resolv.conf. To manage man:resolv.conf(5) in a
# different way, replace this symlink by a static file or a different symlink.
#
# See man:systemd-resolved.service(8) for details about the supported modes of
# operation for /etc/resolv.conf.
nameserver 127.0.0.1
nameserver 127.0.0.1
nameserver 1.1.1.1
# Too many DNS servers configured, the following entries may be ignored.
nameserver 1.0.0.1
search .
My suggestion for fixing this is to see if the file /run/systemd/resolve/stub-resolv.conf exists, using cat, ls, or other command.
If it doesn't try create one using either example above.
Make the files owned by the systemd-resolve user and group:
sudo chown systemd-resolve:systemd-resolve /run/systemd/resolve/stub-resolv.conf
Or see if /run/systemd/resolve/resolv.conf exists and use that.
Create the symbolic link from that back to /etc/resolv.conf
sudo ln -s /run/systemd/resolve/stub-resolv.conf /etc/resolv.conf
Then restart the resolved service:
sudo systemctl reload-or-restart systemd-resolved.service
If that doesn't work then you can try:
sudo ln -s /run/systemd/resolve/resolv.conf /etc/resolv.conf
Then restart the resolved service.
If that doesn't work then I don't have the knowledge to fix. Sorry.