Mikrotik router, have to set des­ti­na­tion nat rule in Firewall..

exam­ple : I wan­to to conect to lolal PC 192.168.1.101 from inter­net, I know out­side ip on router 69.69.69.69
and I want to con­nect to port 5900 on local PC.

COMMAND :

/ip firewall nat add chain=dstnat dst-address=69.69.69.69 protocol=tcp dst-port=5900 \
action=dst-nat to-addresses=192.168.1.101 to-ports=5900

SOURCE