@MoeIbrahim 

This sounds most un-usual as that IP that you mentioned it chagned to 100.x.x.   appear, well unusal :)

Would you be able to uplaod a few screenshots fo what you are seeing?  namely an image from the router showing hte WAN address and then something from the internet using whats my IP  and we can take a look for you

Also where are you terminating your OPEN VPN?    Have you an internal server that requires port forwarding?

Thank you so much for your quick reply @Philbert 

kindly check those images just took them recent(i'm not sure is you can voom in to check) 

ISP Public IP1 41.226.162.72

Privte router IP 100.65.20.198

as for VPN im using the router as VPN as it has this feature built in 
please advice 

thank you in advance :) 

@MoeIbrahim 

Ok this makes a bit more sense now

Think I know what is going on but havent seen this in years!    This looks to be a case of Double NAT by your ISP, namely 141.226.x.x   address is your ISPs external address (hence why it doenst change) and your individual address is the 100.x.x.x is the one your ISP has specifically assigned to you

You wont get any connection throught the 141 address as this will just NAT you to the 100. address, if you try to connect to 141 address it will drop the connection as it wont know where to NAT the reqest too.   Long story short, take the 100 to be your WAN address

Have you setup any VPN on the router yet?   You shouldnt need to do any NAT if you use the 100.x.x.x address

@Philbert Man your are da best  thank you for the info , so there is no way to call the external ISP IP 144.xxx i guess  i have to stick to 100.XXX. IP assiged to me by ISP

now for VPN i have setup OpenVPN setup on VR600 router fuction and it works if i connect via TCP IP 100.xxx. on my local LAN however it dose not work from external internet because setup is using 100.xxx IP and even thought using DDNS it dose not wotk for the same reason external ISP IP, and i'm not using any NAT for VPN, any idea how can i get this to work? should i change ISP maybe to solve my issue? 

Thank you once more

@MoeIbrahim 

Hey

When setting up the OPen VPN did you select Internet and LAN?

Also you may need to open the VPN Profile and check your IP.. as show below in bold. Import this into an Open VPN on ur mobile adn give it a whirl

persist-tun
verb 3
remote 10x.xxx.xxx.xxx 1194
<ca>
-----BEGIN CERTIFICATE-----

And lastly.. yeah its unusual for your ISP to setup that way, you could try calling them to make sure its ok their side.

@Philbert kindly check my VPN setting 

also VPN client file

verb 3
remote 100.65.3.68 1194
<ca>

thank you 

@MoeIbrahim 

Looks good... Just pointing out you have a 10.x.x.x subnet on your VPN...  might be better setting this to 192.168.x.x closer to your LAN IP range..

Say LAN is 192.168.1.x    VPN   192.168.2.x

@Philbert it worked finally  i have contacted my ISP and they assigned me public IP and now this static IP reflect on my router rather than 100.xxx all working well 

Thank you so much for you support