Hello,
i got problem, on builds of VyOS based on PRE 4.11 kernel, NAT rules like:

show nat destination 
 rule 10 {
     destination {
         address 10.45.6.0/24
     }
     inbound-interface vtun1
     translation {
         address 192.168.100.0/24
     }
 }

works like a charm, but on builds based on kernel AFTER 4.11 Active FTP wont work...
I came to conclusion that its because of net.ipv4.ip_unprivileged_port_start in new kernel versions.
Am I right? How to configure NAT now?