The Dtrace for the StorageFileWatch contains
[9532] (StorageFileWatch) <16728> EV:H {AwsSdk::EC2MetadataClient} [Trace] Retrieving credentials from http://169.254.169.254/latest/meta-data/placement/availability-zone
[9532] (StorageFileWatch) <16728> EV:H {AwsSdk::WinHttpSyncHttpClient} [Trace] Making GET request to uri http://169.254.169.254/latest/meta-data/placement/availability-zone
[9532] (StorageFileWatch) <16728> EV:H {AwsSdk::WinHttpConnectionPoolMgr} [Info] Attempting to acquire connection for 169.254.169.254:80
...
[9532] (StorageFileWatch) <16728> EV:H {AwsSdk::EC2MetadataClient} [Error] Can not retrive resource from http://169.254.169.254/latest/meta-data/placement/availability-zone
[9532] (StorageFileWatch) <16728> EV:H {AwsSdk::EC2MetadataClient} [Info] Unable to pull region from instance metadata service
...
Enterprise Vault uses AWS SDK to connect to any compatible S3 devices. The above mentioned errors occur when the target S3 device is not hosted on AWS data centers. More specifically, such calls are made to check the AWS EC2 instance metadata.
According to the AWS knowledge base https://docs.aws.amazon.com/cli/latest/userguide/cli-configure-envvars.html it is possible to implement the system variable AWS_EC2_METADATA_DISABLED=true
For each Enterprise Vault Server, define a new System variable as follows:
1. From the Control Panel, search for System and then click the Edit the system environment variables option.

2. Open Environment Variables...
3. Within System variables, create the AWS_EC2_METADATA_DISABLED to TRUE

4. Click OK and restart the Enterprise Vault services by restarting the Enterprise Vault Admin Service.