"Retrieve Guestbook Responses for a Dataverse Collection" fails for some collections

[jggautier]

Trying to run the "Retrieve Guestbook Responses for a Dataverse Collection" endpoint to get the very large guestbooks of two collections (https://dataverse.harvard.edu/dataverse/covid-rt and https://dataverse.harvard.edu/dataverse/) failed after running for exactly 2 minutes and 20 seconds. Both times the following error message was returned:

curl: (22) The requested URL returned error: 504

The curl command I used in my Mac terminal was
curl -O -J -f -H X-Dataverse-key:APIKEY https://dataverse.harvard.edu/api/dataverses/ALIAS/guestbookResponses, where ALIAS was the alias of the collection (covid-rt or data_ncov) and APIKEY was the APIKEY for my superuser account.

The Harvard Dataverse Repository was at v5.6.

I was able to use the command to get the guestbook of another collection in the repository that had much fewer guestbook responses (and that number matched the results of a database query I did to get that collection's guestbook responses :)