Simple port forward not working?

Hello,
have RB962UiGS (v6.41.4). In NAT have some rules and port works fine (added ports some weeks ago). Today I need to open port 55010 (for one app service in Synology) but it doesn’t work.
IP of Synology is 10.31.0.102.

IP - Addresses

Flags: X - disabled, I - invalid, D - dynamic 
 #   ADDRESS            NETWORK         INTERFACE                                                   
 0   10.31.0.1/24       10.31.0.0       bridge1
 1 D xxx.xxx.xxx.xxx/32   xxx.xxx.xxx.xxx  pppoe-out1

IP - Pool

/ip pool
add name=dhcp_pool0 ranges=10.31.0.2-10.31.0.254
add name=vpn_pool ranges=10.31.10.2-10.31.10.10

NAT

add action=dst-nat chain=dstnat comment="Test port" dst-port= 55010 in-interface=\
    pppoe-out1 protocol=tcp to-addresses=10.31.0.102 to-ports= 55010

It doesn’t work. canyouseeme.org shows me port is closed (Reason: Connection refused).
Have opened another port (53505) and it works fine.

Tried to forward other ports like 2000, 25000, 30000, 45000, 55555 but canyouseeme.org still shows me ports as closed.



Any idea what is bad please? Have dynamic public IP

Is app on 10.31.0.102 running and accepting connections?

yeah that was a problem. App was not running. After running port works fine. Thank you