Please resolve my problem

This is mostly identity/access issue.

 

In IIS, website runs under AppPool identity. 

Check which appPoool your website has.

Check which identity\account your appPoool is running.

Check if that account has access granted to NAS drive. Check if recently the password for the account is changed or not, if so update in AppPool.

 

Check IIS logs, logs for the website and also evenviewr for error logged, you can exact error there. 

From  you localhost - either your id has access to NAS or it is in same network.

 

Thanks,

Tushar