Google App Script UrlFetchApp frequent “address un

Question

I'm using UrlFetchApp for API requests.

     var url = "https://api.bol.com/catalog/v4/search/?....
     var response = UrlFetchApp.fetch(url);

I need to make 1 API request for each item (unfortunately no way around that).

With few items I don't seem to have a problem. When I have over 20 items I often get an "address unavailable" error.

I only have this issue when using Google Spreadsheets, so I'm quite sure the problem lies there. From my server I can do hundreds of requests in a row without issue.

I've tried putting in a delay with using Utilities.sleep to slow down the request rate. That doesn't seem to be the issue.

How to get rid of this error?