The same issue as described here a year ago:
NetworkManager unable to store/edit vpnc, tab blank
still persists, even in a recent fresh installation (6.18 xfce).
The only workaround I found is to keep my parameters in a config-file* for command
sudo vpnc --debug 1 myvpn.conf
(stored safely until needed), but I found that command
sudo vpnc-disconnect
does not properly clean-up - especially the DNS settings - (different from network manager on a system installed earlier, where the vpn was created also long ago) so that my ‘dirty’ workaround to fix this is to disable all networks after disconnecting the vpn and then re-connecting, what causes the IP, mask, GW and DNS to be freshly learned.
Is there any way to add my vote for a fix? On the cited bugreport I see that it persists since 2024, but I have no login here:
Blank VPN tab when creating or editing connection in nm-connection-editor
Many thanks,
Dirk
*) For the courious: I used the example from the man page with user name also used as ‘group name’ (IPsec ID).