Troubleshooting Tip: Error 'vpn_connection:1335 Config routing table failed' when trying to connect SSL-VPN via FortiClient on KUbuntu 23.04

[Umer221]

Description	This article describes how to troubleshoot an issue with FortiClient on KUbuntu 23.04 where users experience a failure to connect while the error 'vpn_connection:1335 Config routing table failed' appears in the FortiGate CLI.
Scope	FortiClient, FortiOS, KUbuntu 23.04.
Solution	If users running FortiClient on KUbuntu 23.04 are unable to connect SSL-VPN, run the following commands in the FortiGate CLI: diag debug reset   diag deb dis diagnose debug application fnbamd 255  diagnose debug application sslvpn -1  diagnose debug console timestamp enable  diagnose debug enable     Look for the error 'vpn_connection:1335 Config routing table failed' as shown in the following screenshot: Run the following script before connecting to SSL-VPN again (It will loop around until it can bring up the VPN and then finish): #!/bin/bash echo "Try to connect to the VPN now" x=99 while [ $x -ne 0 ] do echo "Waiting for VPN connection..." sleep 1 connection=$(nmcli connection show | grep -oP '^vpn\S*') x=$? done echo "VPN connection $connection was created! Waiting for 'device-reapply'..." x=99 while [ $x -ne 0 ] do nmcli -f GENERAL.STATE con show $connection 2> /dev/null x=${PIPESTATUS[0]} sleep 1 echo "Still waiting..." done echo "Device is unmanaged. Setting it to 'up' again..." nmcli con up $connection 2> /dev/null echo "Done."