SAP Browser Access from Outside

Hi all,

I am trying to configure SAP Browser access to be available from outside network. I have already configured port forwarding and i am able to access to dispatcher and SLD from outside. But when i access to dispatcher it redirects to SLD service which picks the link from SLD-Config file in C:\Program Files (x86)\SAP\SAP Business One BAS GateKeeper\tomcat\conf but if i change the IP in the file it redirects correctly but in server service is not started correctly, i think its because public address is not accessible in server it self. (service starts but sap b1 exe is not running in server).

I have tried using External Mapping in SLD configurations but unable access from outside. But if i use a vpn service its working. So is it because public ip is not accessible in internal network? and how do i sort this out?

Thanks & Regards