kernels 4.16 release candidates and 4.15 have broken xl2tpd with a ENODEV (No such device) error, see: https://github.com/xelerance/xl2tpd/issues/147 As mentioned in that github xl2tpd issue, I've submitted a pull request that fixes the bug. It is based on xl2tpd-1.3.8-saref.patch in Fedora's xl2tpd RPM spec file, except it doesn't attempt to obtain the ancillary IP_PKTINFO data, so does pretty much what xl2tpd running on non-linux operating systems do. I've requested a new xl2tpd release which has the pull request, but don't know how long it will be for the new release. It would be great if Fedora 26, 27 and EPEL7 xl2tpd packages are updated to the next new release or have a patch based on the pull request.
xl2tpd-1.3.8-3.el7 has been submitted as an update to Fedora EPEL 7. https://bodhi.fedoraproject.org/updates/FEDORA-EPEL-2018-8beb831755
xl2tpd-1.3.8-7.fc28 has been submitted as an update to Fedora 28. https://bodhi.fedoraproject.org/updates/FEDORA-2018-96c9c68f33
xl2tpd-1.3.8-7.fc27 has been submitted as an update to Fedora 27. https://bodhi.fedoraproject.org/updates/FEDORA-2018-91225f9e39
xl2tpd-1.3.8-7.fc26 has been submitted as an update to Fedora 26. https://bodhi.fedoraproject.org/updates/FEDORA-2018-3095b294d1
xl2tpd-1.3.8-3.el7 has been pushed to the Fedora EPEL 7 testing repository. If problems still persist, please make note of it in this bug report. See https://fedoraproject.org/wiki/QA:Updates_Testing for instructions on how to install test updates. You can provide feedback for this update here: https://bodhi.fedoraproject.org/updates/FEDORA-EPEL-2018-8beb831755
xl2tpd-1.3.8-7.fc26 has been pushed to the Fedora 26 testing repository. If problems still persist, please make note of it in this bug report. See https://fedoraproject.org/wiki/QA:Updates_Testing for instructions on how to install test updates. You can provide feedback for this update here: https://bodhi.fedoraproject.org/updates/FEDORA-2018-3095b294d1
xl2tpd-1.3.8-7.fc27 has been pushed to the Fedora 27 testing repository. If problems still persist, please make note of it in this bug report. See https://fedoraproject.org/wiki/QA:Updates_Testing for instructions on how to install test updates. You can provide feedback for this update here: https://bodhi.fedoraproject.org/updates/FEDORA-2018-91225f9e39
xl2tpd-1.3.8-7.fc28 has been pushed to the Fedora 28 testing repository. If problems still persist, please make note of it in this bug report. See https://fedoraproject.org/wiki/QA:Updates_Testing for instructions on how to install test updates. You can provide feedback for this update here: https://bodhi.fedoraproject.org/updates/FEDORA-2018-96c9c68f33
xl2tpd-1.3.8-7.fc26 has been pushed to the Fedora 26 stable repository. If problems still persist, please make note of it in this bug report.
xl2tpd-1.3.8-7.fc27 has been pushed to the Fedora 27 stable repository. If problems still persist, please make note of it in this bug report.
xl2tpd-1.3.8-7.fc28 has been pushed to the Fedora 28 stable repository. If problems still persist, please make note of it in this bug report.
xl2tpd-1.3.8-3.el7 has been pushed to the Fedora EPEL 7 stable repository. If problems still persist, please make note of it in this bug report.