Wireguard client on Ubuntu Budgie

I am not sure if this belongs here. I have PiVPN-Wireguard running on my UB 20.04.1 desktop. I have .conf files for clients. On Android, I can connect without issues.

With a laptop running UB 20.04.1 I am trying to connect via Wireguard. Using the same .conf file or a newly generated one, I cannot connect. The issue does not lie with Wireguard:

$ sudo systemctl status wg-quick@Obelix.service
● wg-quick@Obelix.service - WireGuard via wg-quick(8) for Obelix
     Loaded: loaded (/lib/systemd/system/wg-quick@.service; enabled; vendor preset: enabled)
     Active: failed (Result: exit-code) since Sat 2020-09-26 16:52:13 WEST; 5s ago
       Docs: man:wg-quick(8)
             man:wg(8)
             https://www.wireguard.com/
             https://www.wireguard.com/quickstart/
             https://git.zx2c4.com/wireguard-tools/about/src/man/wg-quick.8
             https://git.zx2c4.com/wireguard-tools/about/src/man/wg.8
    Process: 25078 ExecStart=/usr/bin/wg-quick up Obelix (code=exited, status=127)
   Main PID: 25078 (code=exited, status=127)

sep 26 16:51:52 Idefix wg-quick[25091]: Temporary failure in name resolution: `obelix.cloud:51822'. Trying again in 2.49 seconds...
sep 26 16:52:04 Idefix wg-quick[25091]: Temporary failure in name resolution: `obelix.cloud:51822'. Trying again in 2.99 seconds...
sep 26 16:52:12 Idefix wg-quick[25078]: [#] ip -4 address add 10.6.0.4/24 dev Obelix
sep 26 16:52:12 Idefix wg-quick[25078]: [#] ip link set mtu 1420 up dev Obelix
sep 26 16:52:13 Idefix wg-quick[25789]: [#] resolvconf -a Obelix -m 0 -x
sep 26 16:52:13 Idefix wg-quick[25791]: /usr/bin/wg-quick: line 31: resolvconf: command not found
sep 26 16:52:13 Idefix wg-quick[25078]: [#] ip link delete dev Obelix
sep 26 16:52:13 Idefix systemd[1]: wg-quick@Obelix.service: Main process exited, code=exited, status=127/n/a
sep 26 16:52:13 Idefix systemd[1]: wg-quick@Obelix.service: Failed with result 'exit-code'.
sep 26 16:52:13 Idefix systemd[1]: Failed to start WireGuard via wg-quick(8) for Obelix.

And journalctl:

asterix@Idefix:/lib/systemd/system$ sudo journalctl -xe
-- Defined-By: systemd
-- Support: http://www.ubuntu.com/support
-- 
-- A start job for unit NetworkManager-dispatcher.service has begun execution.
-- 
-- The job identifier is 2780.
sep 26 16:52:13 Idefix dbus-daemon[901]: [system] Successfully activated service 'org.freedesktop.nm_dispatcher'
sep 26 16:52:13 Idefix systemd[1]: Started Network Manager Script Dispatcher Service.
-- Subject: A start job for unit NetworkManager-dispatcher.service has finished successfully
-- Defined-By: systemd
-- Support: http://www.ubuntu.com/support
-- 
-- A start job for unit NetworkManager-dispatcher.service has finished successfully.
-- 
-- The job identifier is 2780.
sep 26 16:52:13 Idefix NetworkManager[903]: <info>  [1601135533.0539] device (Obelix): state change: ip-check -> secondaries (reason 'none', sys-iface-state: 'external')
sep 26 16:52:13 Idefix NetworkManager[903]: <info>  [1601135533.0544] device (Obelix): state change: secondaries -> activated (reason 'none', sys-iface-state: 'external')
sep 26 16:52:13 Idefix NetworkManager[903]: <info>  [1601135533.0570] device (Obelix): Activation: successful, device activated.
sep 26 16:52:13 Idefix NetworkManager[903]: <info>  [1601135533.0773] device (Obelix): state change: activated -> unmanaged (reason 'unmanaged', sys-iface-state: 'removed')
sep 26 16:52:13 Idefix nm-dispatcher[25839]: run-parts: failed to stat component /etc/network/if-post-down.d/avahi-daemon: No such file or directory
sep 26 16:52:13 Idefix systemd[1]: wg-quick@Obelix.service: Main process exited, code=exited, status=127/n/a
-- Subject: Unit process exited
-- Defined-By: systemd
-- Support: http://www.ubuntu.com/support
-- 
-- An ExecStart= process belonging to unit wg-quick@Obelix.service has exited.
-- 
-- The process' exit code is 'exited' and its exit status is 127.
sep 26 16:52:13 Idefix systemd[1]: wg-quick@Obelix.service: Failed with result 'exit-code'.
-- Subject: Unit failed
-- Defined-By: systemd
-- Support: http://www.ubuntu.com/support
-- 
-- The unit wg-quick@Obelix.service has entered the 'failed' state with result 'exit-code'.
sep 26 16:52:13 Idefix systemd[1]: Failed to start WireGuard via wg-quick(8) for Obelix.
-- Subject: A start job for unit wg-quick@Obelix.service has failed
-- Defined-By: systemd
-- Support: http://www.ubuntu.com/support
-- 
-- A start job for unit wg-quick@Obelix.service has finished with a failure.
-- 
-- The job identifier is 2706 and the job result is failed.
sep 26 16:52:13 Idefix sudo[25075]: pam_unix(sudo:session): session closed for user root
sep 26 16:52:18 Idefix sudo[25928]:  asterix : TTY=pts/0 ; PWD=/usr/lib/systemd/system ; USER=root ; COMMAND=/usr/bin/systemctl status wg-quick@Obelix.service
sep 26 16:52:18 Idefix sudo[25928]: pam_unix(sudo:session): session opened for user root by (uid=0)
sep 26 16:52:18 Idefix sudo[25928]: pam_unix(sudo:session): session closed for user root
sep 26 16:52:23 Idefix systemd[1]: NetworkManager-dispatcher.service: Succeeded.
-- Subject: Unit succeeded
-- Defined-By: systemd
-- Support: http://www.ubuntu.com/support
-- 
-- The unit NetworkManager-dispatcher.service has successfully entered the 'dead' state.
sep 26 16:52:33 Idefix sudo[26073]:  asterix : TTY=pts/0 ; PWD=/usr/lib/systemd/system ; USER=root ; COMMAND=/usr/bin/journalctl -xe
sep 26 16:52:33 Idefix sudo[26073]: pam_unix(sudo:session): session opened for user root by (uid=0)

It seems something goes wrong right after starting Wireguard?

That is looking for “resolvconf” but is failing - is that installed on your machine? sudo apt install resolvconf

fwiw, the preinstalled network manager in budgie handles most .conf files pretty well too