A conflict with a new module (altera_cvp) added to the Linux Kernel 4.14 and newer, leads to the problem, that syn1588® PCIe NIC devices are no longer visible in your system. This issue is caused by the altera_cvp driver that erroneously blocks other units in the system. We already informed the responsible Linux maintainers.
In the meanwhile we provide you a workaround, that removes the buggy altera_cvp driver and installs the Oregano Systems syn1588® drivers again. There is a syn1588® Application Note: Issues with Linux kernel version 4.14 and altera_cvp module that describes the required action and there is a patch file: Issues with Linux kernel version 4.14 and altera_cvp module