Dear Jitendra,
1. Are you able to run service document url (OData service exposed via IGW) ??
==> Yes i am able to run the URL
2. Is that host/port of endpoint not same as SMP Admin host/port ? (by default port:8083)
==> it is same as host/port but i have changed it to (8086) because 8083 was in used somewhere. I have tried with IP/Domain name as well but the result is same
3. Did you select 'Internal' checkbox under 'Backend' while configuring app id?
==> Yes i have selected the Internal checkbox