Prevent "Ignore denied clients" and "Failover Peer IP" from being combined in the DHCP server settings for IPv4. The daemon fails to start when configured in this way, it apparently only allows "allow" or "deny" in failover mode. Fixes #5898
Related issues
Bug #5898: services_dhcp.php: "Ignore denied clients" is incompatible with failover
Prevent "Ignore denied clients" and "Failover Peer IP" from being combined in the DHCP server settings for IPv4. The daemon fails to start when configured in this way, it apparently only allows "allow" or "deny" in failover mode. Fixes #5898