I've built a custom Symfony application that uses Guzzle for cUrl requests. The functionality uses the all contacts call to retrieve the VID's from the contacts and then loops over those. For each VID that we have I call upon the contact by vid call to get the contact in question, and save some information from that contact to the database.
This goes fine. In fact it went fine most of the time. But at the day of this writing, 20-07-2018, it seems that I get a 524 Origin Time-out response every time after about 90 contacts or so.
Looking for a solution, I've sliced the batch size of the amount of contacts that I'm getting per 'getting all contacts requests' by half to 50. They used to be 100.
This didn't help. I don't really know where to go from here and wonder if the issue might be from your side.
If you need any additional information, contact me. I'll see if I can get it for you.