Microsoft Graph API Reports > lots of 504 GatewayTimeout error

Hello,

I'm using Microsoft Graph API to download the activity reports from Office 365 ( https://developer.microsoft.com/en-us/graph/docs/api-reference/beta/resources/report ) in a format JSON.

But I'm facing an issue : I get a LOT of errors 504 GATEWAYTIMEOUT.

I have to try again the request 2 or 3 or 4 or even more times to make it succeed

For example : 

(http 504 GatewayTimeout) Response Error :
Endpoint : https://graph.microsoft.com/beta
Api Url : /reports/getYammerActivityUserDetail(date=2018-04-16)?$format=application/json&$top=500
Method : GET

{
"error": {
"code": "UnknownError",
"message": "",
"innerError": {
"request-id": "9fdc7b24-2d66-4e9f-92d5-ef281b2ecbc9",
"date": "2018-04-18T15:09:06"
}
}
}

Is that a known issue , or is there a way to avoid this ?

Thank you !