Possibly caused by the last updates.
anacron is throwing the following e-mail daily:
/etc/cron.daily/pulledpork:
Job for suricata.service invalid.
I think as a result of these messages in /var/log/messages:
Jul 1 04:35:29 Nethserver systemd: [/usr/lib/systemd/system/suricata.service:17
] Unknown lvalue 'MemoryDenyWriteExecute' in section 'Service'
Jul 1 04:35:29 Nethserver systemd: [/usr/lib/systemd/system/suricata.service:18
] Unknown lvalue 'LockPersonality' in section 'Service'
Jul 1 04:35:29 Nethserver systemd: [/usr/lib/systemd/system/suricata.service:19
] Unknown lvalue 'ProtectControlGroups' in section 'Service'
Jul 1 04:35:29 Nethserver systemd: [/usr/lib/systemd/system/suricata.service:20
] Unknown lvalue 'ProtectKernelModules' in section 'Service'
.
.
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Jul 1 04:35:46 Nethserver systemd: Unit suricata.service cannot be reloaded because it is inactive.
Cheers.