Nextcloud Security Scan broken since weeks

Summary:

Nextcloud Security Scan broken since weeks

Steps to Reproduce:

1. Navigate to https://scan.nextcloud.com
2. Enter the domain of your Nextcloud instance
3. Click the Scan button

Expected Results:

See the last cached security report of that instance with a button to rescan for updating the report.

Actual Results:

Page always displays “Host not found” indicating a DNS issue on the scanning server.

Regression:

This did work fine a few weeks ago.

Notes:

I've tried with multiple of the several Nextcloud instances I admin. All of them actually get scanned but the Scan server always returns “Host not found”.

I was instructedx to report the issue here by the official Nextcloud account on Mastodon. Reference link:
https://mastodon.xyz/@nextcloud/114875147964785331

Version Information:

Does not apply. It's independent of the Nextcloud Server. This problem applies to the SCAN server, not any Nextcloud instance. (See Notes.)

Start at https://scan.nextcloud.com and reproduce the scan with one of the affected Nextcloud instance domains. Investigate why the scanning server reports “Host not found” despite completing scans; done means cached reports display correctly and rescanning updates them.