In lot of cases there is a situation when RB router is behind other router inside local lan.
In situation:
INTERNET > |upnp router| <-private lan-> |mikrotik RB| > user
upnp router: have public ip, upnp support and serve private network (RFC 1918)
Mikrotik RB: have upnp support also.
But not communicate with upper level router when UPnP port mapped
Already have detection for this cases:
/ip cloud> pr
ddns-enabled: yes
update-time: yes
public-address: 151.237.98.102
dns-name: xxxxxxxxxxxxxxx.sn.mynetname.net
status: updated
warning: DDNS server received request from IP xxx.yyy.zzz.102 but your
local IP was 192.168.1.37; DDNS service might not work.