--- title: 'Troubleshooting L2TP/IPsec connection errors "Could not add IPsec connection" and "no acceptable traffic selectors found"' url: 'https://ra1ahq.blog/en/ustranenie-oshibok-podklyucheniya-l2tp-ipsec-could-not-add-ipsec-connection-i-no-acceptable-traffic-selectors-found' markdown: 'https://ra1ahq.blog/en/ustranenie-oshibok-podklyucheniya-l2tp-ipsec-could-not-add-ipsec-connection-i-no-acceptable-traffic-selectors-found.md' lang: en date: '2026-02-20' description: 'After upgrading to Linux Mint 22.3 "Zena" based on Ubuntu 24.04 LTS "Noble," my L2TP/IPsec VPN connection to my home network stopped working. Here''s the solution. Note T' taxonomy: category: - blog tag: - Linux - безопасность archives_month: - feb_2026 archives_year: - '2026' --- 20 February 2026 15:00 ### Troubleshooting L2TP/IPsec connection errors "Could not add IPsec connection" and "no acceptable traffic selectors found" [Linux](https://ra1ahq.blog/en/tag:Linux), [безопасность](https://ra1ahq.blog/en/tag:%D0%B1%D0%B5%D0%B7%D0%BE%D0%BF%D0%B0%D1%81%D0%BD%D0%BE%D1%81%D1%82%D1%8C) 20 February 2026 15:00 After upgrading to Linux Mint 22.3 "Zena" based on Ubuntu 24.04 LTS "Noble," my L2TP/IPsec VPN connection to my home network stopped working. Here's the solution. ### Note This article describes connecting to a home VPN, which I have using the L2TP/IPsec (IKEv1) type. I previously used the [tunnel to stream audio from a radio speaker to my smartphone via the SoundWire app](https://ra1ahq.blog/en/translyaciya-zvuka-soundwire). This article is not an advertisement for VPN internet technologies, but rather describes a solution to a technical issue with Linux OS. ### Introduction The error "Could not add IPsec connection."\*\* appears in the journalctl log when attempting to connect to an L2TP over IPsec VPN. It appears as if an attempt is made to connect to the VPN and then disconnects after a few seconds. The VPN connection is reset to the wired connection without displaying an error message. The journalctl log shows the NetworkManager warning "no acceptable traffic selectors found."\*\* Connecting to an L2TP/IPsec VPN on Linux Green operating system based on Linux Mint 21.3 *doesn't produce this error*. The connection parameters are the same in Linux Mint 22.3 and 21.3. ### 0. Linux version with the problem ``` lsb_release -a ``` ``` No LSB modules are available. Distributor ID: Linuxmint Description: Linux Mint 22.3 Release: 22.3 Codename: zena ``` ### 1. NetworkManager "L2TP" Plugin Update This update does not fix the NetworkManager bug, but it does allow L2TP/IPsec VPN connections to function properly. Linux Mint has an outdated version of the networkmanager-l2tp plugin. I updated it to the latest version: 1.1 Adding the ppa:nm-l2tp/network-manager-l2tp PPA repository to the system: ``` sudo add-apt-repository ppa:nm-l2tp/network-manager-l2tp ``` 1.2 Adding a repository signing key ``` gpg --keyserver keyserver.ubuntu.com --recv 80B70870665AB177 gpg --export 80B70870665AB177 | sudo tee /etc/apt/trusted.gpg.d/networkmanager-l2tp.gpg > /dev/null ``` The netoworkmanager repository key was saved to the keyring in the file networkmanager-l2tp.gpg/ 1.3 Editing the networkmanager-l2tp repository description file, which is contained in the current version of Linux Mint in the file `/etc/apt/sources.list.d/nm-l2tp-network-manager-l2tp-noble.list`: ``` cd /etc/apt/sources.list.d/ ls sudo nano nm-l2tp-network-manager-l2tp-noble.list ``` In the file, I replaced the line in "signed-by" from *noble/keyrings* to /etc/apt/trusted.gpg.d/networkmanager-l2tp.gpg : `deb [signed-by=/etc/apt/trusted.gpg.d/networkmanager-l2tp.gpg] https://ppa.launchpadcontent.net/nm-l2tp/network-manager-l2tp/ubuntu noble main` ``` sudo apt update sudo apt upgrade ``` 1.4 **Reinstalling the "networkmanager-l2tp" package** ``` sudo apt install --reinstall network-manager-l2tp network-manager-gnome ``` The visual difference between the new version of the networkmanager-l2tp plugin and the old one is the text fields with a gradient or shadow effect. ### 2. Replacing the LibreSwan package with StrongSwan Since many guides recommend replacing LibreSwan with StrongSwan, I followed the same approach. ``` sudo apt remove libreswan ``` Removing the libreswan package will automatically install the StrongSwan component for IPsec/L2TP VPN. ### 3. Editing the /etc/strongswan.conf configuration file ``` sudo nano /etc/strongswan.conf ``` The file should look like this: ``` # strongswan.conf - strongSwan configuration file # # Refer to the strongswan.conf(5) manpage for details # # Configuration changes should be made in the included files charon { load_modular = yes plugins { include strongswan.d/charon/*.conf } } include strongswan.d/*.conf ``` Where the default `load_modular = no` has been replaced with `load_modular = yes`. When load\_modular is enabled, the plugin list is generated dynamically, based solely on the loading settings specific to each plugin. This list completely replaces the list created during compilation. [Source](https://docs.strongswan.org/docs/latest/plugins/pluginLoad.html) Press Ctrl+O, Ctrl+X. As we can see, the strongswan.conf file references the configuration files in the **strongswan.d** subdirectory. ### 4. Editing the /etc/strongswan.d/charon.conf configuration file ``` sudo nano /etc/strongswan.d/charon.conf ``` Find the line **"cisco\_unity"** and assign it the value **"no"** instead of "yes" and remove the comment sign (#) at the beginning of the line. It should look like this: **`cisco_unity = no`** This line disables the Cisco flag, which affects L2TP/IPsec (IKEv1) connection establishment. The `charon.conf` file without the comment lines looks like this: ``` charon { cisco_unity = no crypto_test { } host_resolver { } leak_detective { } processor { priority_threads { } } start-scripts { } stop-scripts { } tls { } x509 { } } ``` Save the file: Ctrl+O, Ctrl+X. ### 5. Creating the file `/etc/strongswan.d/charon/unity.conf` If the file doesn't exist, create it: ``` sudo nano /etc/strongswan.d/charon/unity.conf ``` ``` unity { # Whether to load the plugin. Can also be an integer to increase the # priority of this plugin. load = no } ``` Press Ctrl+O, Ctrl+X. We see that Unity loading is disabled: **`load=no`**. The Unity plugin provides libcharon support for some parts of the Cisco Unity Extensions for the IKEv1 protocol. ### 6. Diagnostics The standard `journalctl -xe` command doesn't provide complete information about NetworkManager errors. If a connection cannot be established, the log displays only one message: "Could not add ipsec connection.", without specifying the reason. In a separate terminal window, run the command to display a detailed NetworkManager log: ``` sudo journalctl -f 20 --no-hostname _SYSTEMD_UNIT=NetworkManager.service + _COMM=kl2tpd + SYSLOG_IDENTIFIER=pppd ``` ### 7. Testing the Connection To "start" the connection, run in the terminal ``` sudo nmcli c up --ask "VPN IPsec" ``` where "VPN IPsec" is the name of the L2TP/IPsec connection. Alternatively, you can enable the VPN connection through the NetworkManager plugin graphical interface in the system tray (near the clock). If the connection is successful, nmcli will display the following message in the terminal: *"Connection successfully activated (active D-Bus path: /org/freedesktop/NetworkManager/ActiveConnection/18)"* Or, a pop-up message indicating a successful connection will briefly appear in the upper corner of the screen. The Ethernet connection icon in the system tray will change to a lock symbol. If the connection was unsuccessful, check the extended NetworkManager log (in the current or another Terminal window): ``` sudo journalctl -f 20 --no-hostname _SYSTEMD_UNIT=NetworkManager.service + _COMM=kl2tpd + SYSLOG_IDENTIFIER=pppd ``` When successfully connecting to an L2TP/IPsec (IKEv1) VPN, the terminal window periodically displays messages about "keep-alive" packets. **Source:** - [Know issues of NetworkManager](https://github.com/nm-l2tp/NetworkManager-l2tp/wiki/Known-Issues#strongswan-no-acceptable-traffic-selectors-found) - [Solved - Help Connecting to L2TP VPN in Linux Debian 12](https://www.linux.org/threads/help-connecting-to-l2tp-vpn-in-linux-debian-12.53466/) ### Related publications [ ![](https://ra1ahq.blog/images/f/3/a/2/c/f3a2c07ef5b32c0308ab703405a5a5ca87b75283-archer-ac600-728.webp) Installing the kernel driver for the TP-Link Wi-Fi adapter after updating the Debian OS ](https://ra1ahq.blog/en/ustanovka-draivera-yadra-dlya-wi-fi-adaptera-tp-link-posle-obnovleniya-os-debian) [ ![](https://ra1ahq.blog/images/d/2/5/c/7/d25c7282750b398f71041fb8b90640b692e7e4b8-decibelfmtitle.png) Linux Cinnamon Desktop Applets for Listening to Internet Radio Stations ](https://ra1ahq.blog/en/applety-dlya-rabochego-stola-linux-cinnamon-dlya-proslushivaniya-internet-radiostancii) [ ![No picture](https://ra1ahq.blog/user/themes/mytheme/images/no-image.png) Passing a parameter to a Linux module/driver ](https://ra1ahq.blog/en/peredacha-parametra-modulyu-draiveru-linux) [ ![](https://ra1ahq.blog/images/5/c/4/e/a/5c4ea9c8c3f0b4dd890116d8fe7cbadfdb9814ba-archer-ac600.webp) Installing the TP-Link Archer T600U Nano Wi-Fi adapter driver in Debian 13 "Trixie" ](https://ra1ahq.blog/en/ustanovka-draivera-wi-fi-adaptera-tp-link-archer-t600u-nano-v-debian-13-trixie) [ ![](https://ra1ahq.blog/images/b/f/f/0/f/bff0f99f5897e0420fac9a6eef7254247f39c29d-pulseaudio-equalizer.png) Installing the audio equalizer pulseaudio-equalizer-ladspa on Linux ](https://ra1ahq.blog/en/ustanovka-v-linux-ekvalaizera-zvuka-pulseaudio-equalizer-ladspa) [ Backward](https://ra1ahq.blog/en/chast-radiolyubitelskikh-veb-saitov-nedostupna-v-internet-iz-rossii "Previuous page") [ Forward ](https://ra1ahq.blog/en/chastoty-lyubitelskoi-sluzhby-dlya-region-r1-evropy-i-rossii "Next page") ## Languages - 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