Port forwarding with PPPOE doesn't work

RouterOS General
1

Hi. I havw RB951Ui-2HND. The internet line is connected to port1, the connection to internet is made via PPPOE. I’ve to setup port forwarding to 192.168.88.244, port 8080.
I have the following configuration in Firewall:

Flags: X - disabled, I - invalid, D - dynamic 
 0    ;;; defconf: masquerade
      chain=srcnat action=masquerade out-interface-list=WAN 
      ipsec-policy=out,none 

 1    chain=dstnat action=dst-nat to-addresses=192.168.88.244 to-ports=8080 
      protocol=tcp in-interface=ether1 src-port="" dst-port=8080 log=no 
      log-prefix=""

Please advice, how to fix my problem.

2

in-interface should be PPPoE client, or you can use dst-address (your public IP) instead of that.
to-ports value is unnecessary, you should use that when internal port is different from external one.

3

Besides what is explained above, the other problem with this rule is src-port=“”, which means src-port=NULL. src-port will never be null, so therefore you will need to adjust this rule; Otherwise, it will never apply.