Currently the server is unavailable due to an ongoing migration to the Atlassian Jira cloud. Open Source projects are not affected and become available again once the migration was completed.
For Qt Company employees please check the list of projects to be migrated: Affected Projects (https://intranet.qt.io/display/QTIT/Migration+for+bugreports#Migrationforbugreports-Affectedprojects).
The lock down remains in place until Sunday evening or earlier if possible.
When Creator can't display a help page, it lists suggestions about checking the network connection:
AFAIK this is outdated since Creator will never try to access non-local documents anymore. These will be opened in the system's browser instead.