How about using Postman?
It helps to verify the response.
I got link data using Postman.
My test steps are below.
1. Get Enterprise Logical ID
I got my enterpse logicalId via API v1.
Request: Post
"https://<vco-fqdn>/portal/rest/enterprise/getEnterprise"
I got enterpriseLogicalId like this.
xxxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx
2. Get Edge Logical ID
I got my edge logicalId via API v1.
Request: Post
https://<vco-fqdn>/portal/rest/enterprise/getEnterpriseEdges
I got edgeLogicalId like this.
yyyyyyyyy-yyyy-yyyy-yyyy-yyyyyyyyyyy
3. Get Link stats
Request: Get
https://{vco-fqdn}//api/sdwan/v2/enterprises/{enterpriseLogicalId}/edges/{edgeLogicalId}/linkStats
