I had used
https://www.yougetsignal.com/tools/open-ports/ site recently to validate the ports and I just did again and got the same results.
23424 reports open
23524 reports as "invalid"
I checked my router's configuration and I DO have both ports defined in port forwarding. Also, I looked in the router's log and it shows both ports as forwarded too, so I have to believe it's something on the server. Also, on the server there is no firewall running (it's a raspberry pi 2-B), and I check the open ports on the server and it shows;
Active Internet connections (only servers)
Proto Recv-Q Send-Q Local Address Foreign Address State PID/Program name
tcp 0 0 0.0.0.0:22 0.0.0.0:* LISTEN 444/sshd
tcp 0 0 0.0.0.0:445 0.0.0.0:* LISTEN 822/smbd
tcp 0 0 0.0.0.0:8895 0.0.0.0:* LISTEN 29841/java
tcp 0 0 0.0.0.0:23423 0.0.0.0:* LISTEN 29841/java
tcp 0 0 0.0.0.0:23424 0.0.0.0:* LISTEN 29841/java
tcp 0 0 0.0.0.0:23523 0.0.0.0:* LISTEN 29841/java
tcp 0 0 0.0.0.0:23524 0.0.0.0:* LISTEN 29841/java
tcp 0 0 127.0.1.1:44331 0.0.0.0:* LISTEN 29841/java
tcp 0 0 0.0.0.0:139 0.0.0.0:* LISTEN 822/smbd
tcp 0 0 0.0.0.0:5900 0.0.0.0:* LISTEN 414/vncserver-x11-c
tcp6 0 0 :::22 :::* LISTEN 444/sshd
tcp6 0 0 :::445 :::* LISTEN 822/smbd
tcp6 0 0 :::139 :::* LISTEN 822/smbd
tcp6 0 0 :::5900 :::* LISTEN 414/vncserver-x11-c
So it seems like all the pieces are in place but something is still missing