I have successfully installed network-manager-l2tp for Ubuntu 16.04 using this guide: https://askubuntu.com/a/797764/578622
I can enter in all information needed and then enable the connection, but after a while it just says "connection failed".
I looked at /var/log/syslog and found the following:
Aug 6 16:43:21 pi-laptop NetworkManager[908]: initiating Main Mode IKE_SA nm-ipsec-l2tp-10981[1] to 193.170.109.20
Aug 6 16:43:21 pi-laptop NetworkManager[908]: generating ID_PROT request 0 [ SA V V V V ]
Aug 6 16:43:21 pi-laptop NetworkManager[908]: sending packet: from 192.168.0.11[500] to 193.170.109.20[500] (280 bytes)
Aug 6 16:43:21 pi-laptop NetworkManager[908]: received packet: from 193.170.109.20[500] to 192.168.0.11[500] (124 bytes)
Aug 6 16:43:21 pi-laptop NetworkManager[908]: parsed ID_PROT response 0 [ SA V V ]
Aug 6 16:43:21 pi-laptop NetworkManager[908]: received NAT-T (RFC 3947) vendor ID
Aug 6 16:43:21 pi-laptop NetworkManager[908]: received FRAGMENTATION vendor ID
Aug 6 16:43:21 pi-laptop NetworkManager[908]: generating ID_PROT request 0 [ KE No NAT-D NAT-D ]
Aug 6 16:43:21 pi-laptop NetworkManager[908]: sending packet: from 192.168.0.11[500] to 193.170.109.20[500] (244 bytes)
Aug 6 16:43:21 pi-laptop NetworkManager[908]: received packet: from 193.170.109.20[500] to 192.168.0.11[500] (304 bytes)
Aug 6 16:43:21 pi-laptop NetworkManager[908]: parsed ID_PROT response 0 [ KE No V V V V NAT-D NAT-D ]
Aug 6 16:43:21 pi-laptop NetworkManager[908]: received Cisco Unity vendor ID
Aug 6 16:43:21 pi-laptop NetworkManager[908]: received XAuth vendor ID
Aug 6 16:43:21 pi-laptop NetworkManager[908]: received unknown vendor ID: 00:99:c1:e5:06:c4:f7:b0:f0:62:e0:82:4f:8e:1a:aa
Aug 6 16:43:21 pi-laptop NetworkManager[908]: received unknown vendor ID: 1f:07:f7:0e:aa:65:14:d3:b0:fa:96:54:2a:50:01:00
Aug 6 16:43:21 pi-laptop NetworkManager[908]: local host is behind NAT, sending keep alives
Aug 6 16:43:21 pi-laptop NetworkManager[908]: generating ID_PROT request 0 [ ID HASH N(INITIAL_CONTACT) ]
Aug 6 16:43:21 pi-laptop NetworkManager[908]: sending packet: from 192.168.0.11[4500] to 193.170.109.20[4500] (100 bytes)
Aug 6 16:43:21 pi-laptop NetworkManager[908]: received packet: from 193.170.109.20[4500] to 192.168.0.11[4500] (84 bytes)
Aug 6 16:43:21 pi-laptop NetworkManager[908]: parsed ID_PROT response 0 [ ID HASH V ]
Aug 6 16:43:21 pi-laptop NetworkManager[908]: received DPD vendor ID
Aug 6 16:43:21 pi-laptop NetworkManager[908]: IKE_SA nm-ipsec-l2tp-10981[1] established between 192.168.0.11[192.168.0.11]...193.170.109.20[193.170.109.20]
Aug 6 16:43:21 pi-laptop NetworkManager[908]: scheduling reauthentication in 10080s
Aug 6 16:43:21 pi-laptop NetworkManager[908]: maximum IKE_SA lifetime 10620s
Aug 6 16:43:21 pi-laptop NetworkManager[908]: generating QUICK_MODE request 2613055945 [ HASH SA No ID ID NAT-OA NAT-OA ]
Aug 6 16:43:21 pi-laptop NetworkManager[908]: sending packet: from 192.168.0.11[4500] to 193.170.109.20[4500] (244 bytes)
Aug 6 16:43:21 pi-laptop NetworkManager[908]: received packet: from 193.170.109.20[4500] to 192.168.0.11[4500] (204 bytes)
Aug 6 16:43:21 pi-laptop NetworkManager[908]: parsed QUICK_MODE response 2613055945 [ HASH SA No ID ID N((24576)) NAT-OA NAT-OA ]
Aug 6 16:43:21 pi-laptop NetworkManager[908]: no acceptable traffic selectors found
Aug 6 16:43:21 pi-laptop NetworkManager[908]: establishing connection 'nm-ipsec-l2tp-10981' failed
Aug 6 16:43:21 pi-laptop NetworkManager[908]: ** Message: strongSwan ready for action.
After that the log continues and displays some information about xl2tp trying to connect, which is interesting because the connection already failed at no acceptable traffic selectors found?
Google just brought up some people saying it's an error in the config file syntax, but I don't believe that's the issue here as all configs were created by the aforementioned network-manager plugin and the log doesn't complain about config errors.
On my Windows system the connection works just fine, although I have to put a radius address in the EAP settings (following the instructions given by the server admin). Could that be a problem? On Android for example it just works out of the box...
Can anyone please explain to me what's happening here and how to fix it? I really need this VPN connection to work under Ubuntu.
