pfSense

Assigned ovpnc interface was chosen as relay interface, config was saved. DHCP relay claimed this interface to be not supported. Then ovpnc was unchecked, service restarted, system rebooted, but DHCP relay still didn't start showing this log:

/status_services.php: The command '/usr/local/sbin/dhcrelay -i vmx1 -i ovpnc1 10.0.13.1' returned exit code '1', the output was 'Requesting: vmx1 as upstream: Y downstream: Y Requesting: ovpnc1 as upstream: Y downstream: Y Internet Systems Consortium DHCP Relay Agent 4.3.6-P1 Copyright 2004-2018 Internet Systems Consortium. All rights reserved. For info, please visit https://www.isc.org/software/dhcp/ Unsupported device type 23 for "ovpnc1" If you think you have received this message due to a bug rather than a configuration issue please read the section on submitting bugs on either our web page at www.isc.org or in the README file before submitting a bug. These pages explain the proper process and the information we find helpful for debugging. exiting.'