Accessing Community server and Document server in LAN/external

[Alexandre]

Hello @sundar
This scenario is a little bit strange

@sundar

2. Use document server to write a custom code , integrate word/excel editor in our application. -
3. using community server API , store the final document back to the folder

Please note that Workspace Community Edition is a ready-to-go portal solution. It doesn’t assume Document server integration to third party app\storage. Please check this description by @Carl here: Unable to integrate Nextcloud with Workspace - #2 by Carl

So, if you are going to integrated DS to your app, please use separate Document server.
If you are independent integrator, you can integrate DS to your app in your own way. Probably these links will be useful:

ONLYOFFICE Api Documentation - How It Works

ONLYOFFICE Api Documentation - Language-specific examples