504 Gateway Timeout (UnknownError) when trying to track changes to a custom calendar

For our backend application, we sync our custom calendars (from our Office 365 tenant) with a local "cache" in our database. We are using the new Delta Queries in Microsoft Graph to track these changes.

Most of the calendars sync correctly, but for some reason there is one single calendar where we consistently hit an error 504 Gateway Timeout

when trying to request events using those nextLink

received from the first request.

First request:

GET https://graph.microsoft.com/v1.0/users/<userId>/calendars/<calendarId>/calendarView/delta?startDateTime=2017-06-10t00%3A00%3A00Z&endDateTime=2018-06-10t00%3A00%3A00Z

First answer:

{
    "@odata.context": "https://graph.microsoft.com/v1.0/$metadata#Collection(event)",
    "@odata.nextLink": "https://graph.microsoft.com/v1.0/users/<userId>/calendars/<calendarId>/calendarView/delta?$skiptoken=R0usmcdvmMuZCBYV0hguCGmIJqcU0n_6jVFWUlNKbXkBKYVlxLSMsISZI5sLLLJyLJF8hZIj0PURpAeP_XxydW_qbMUoFMTXjOpLa8Ta6rxMRA7Wv6IHYfjyLPcDzCbM_hKvTgq8BZaBeJv-a61mebF6X2wT4HqCAGL5lL4nLZabHk1nD9GbWJ0a4Qq0M41_GPYxEi5YNe9u1673SQ1Djw.F85xXB6GjtO7myCQCOgFvzp1G7mQB0BvuHQJyn0CICQ",
    "value": [
        <list of events>
    ]
}

      

        
        
        
      

    

Second query:

GET https://graph.microsoft.com/v1.0/users/<userId>/calendars/<calendarId>/calendarView/delta?$skiptoken=R0usmcdvmMuZCBYV0hguCGmIJqcU0n_6jVFWUlNKbXkBKYVlxLSMsISZI5sLLLJyLJF8hZIj0PURpAeP_XxydW_qbMUoFMTXjOpLa8Ta6rxMRA7Wv6IHYfjyLPcDzCbM_hKvTgq8BZaBeJv-a61mebF6X2wT4HqCAGL5lL4nLZabHk1nD9GbWJ0a4Qq0M41_GPYxEi5YNe9u1673SQ1Djw.F85xXB6GjtO7myCQCOgFvzp1G7mQB0BvuHQJyn0CICQ

Second answer:

504 Gateway Timeout

{
    "error": {
        "code": "UnknownError",
        "message": "",
        "innerError": {
            "request-id": "0784cffb-cba7-424b-be1d-74b2bfef5da1",
            "date": "2017-07-10T09:11:33"
        }
    }
}

      

        
        
        
      

    

I've tried executing the script several times over the last week, but the request consistently fails when using the second page request. Other calendars sync without issue, so I really don't know how to debug issues like this. Is there anything we can do to fix this problem?