Igen, most megkerestem:
OpenVPN 2.6 introduced a change in how ciphers should be specified. The value from --cipher is no more copied to --data-ciphers. In NetworkManager-openvpn this behavior was maintained aiming for backwards compatibility, but it seems it was not a good idea and it was reverted in NetworkManager-openvpn 1.11.0:
https://gitlab.gnome.org/GNOME/NetworkManager-openvpn/-/issues/112
https://gitlab.gnome.org/GNOME/NetworkManager-openvpn/-/merge_requests/64
Workaround:
nmcli connection modify CONNECTION_NAME +vpn.data "data-ciphers = AES-256-CBC"
Real solution: ask your server's admin to update the config and reimport the .ovpn after that:
https://gitlab.gnome.org/GNOME/NetworkManager-openvpn/-/issues/112#note_2191737
Mármint az AES-256-CBC az én esetemre bír relevanciával, de a hibaüzenetekből, logból azt hiszem, látszik. Ugye, a CONNECTION_NAME értelemszerűen az, ami, szóval nem szó szerint értendő.