general routing question

Hello!

I have a NAT rule for dst-nat a port to a inside computer behind mikrotik. When i try to connect from outside network (ex. from my work) to the NATed port all works fine, but when i try to connect from any computer behind the mikrotik router to my public address and NATed port the connection could not be estableshed (as i understand router open ports for the connection incorrectly). How can i fix it?

my routing table:

 #     DST-ADDRESS        PREF-SRC        G GATEWAY         DISTANCE INTERFACE
 0 ADC 87.240.48.0/20     87.240.MY.IP                               inet
 1 ADC 192.168.3.0/24     192.168.3.1                                lan
 2 A S 0.0.0.0/0                          r 87.240.55.193            inet

Connect to the internal address.