Exact domain name, including potential subdomain, is needed in the whitelist to work as wanted. From the link you posted it appears that files are at https://mmp.sub.uni-hamburg.de website.

thanks, it is https://mmp.sub.uni-hamburg.de

@Framawiki Is it ok to use *.uni-hamburg.de?

@Zoranzoki21: Why do you consider using *.uni-hamburg.de? Please provide a rationale.

In T216886#4978545, @Zoranzoki21 wrote:

@Framawiki Is it ok to use *.uni-hamburg.de?

In that case no, you'll need the exact same level of subdomains. For mmp.sub.uni-hamburg.de, the entry *.*.uni-hamburg.de would work.
But if you have no reason to authorize all the two level subdomains I would prefer to only have the exact entry whitelisted.

Ok, so I will add only uni-hamburg.de

Thanks much!

In T216886#5056126, @Zoranzoki21 wrote:

Ok, so I will add only uni-hamburg.de

Thanks much!

As said previously note that exact uni-hamburg.de entry will not wok as excepted. mmp.sub.uni-hamburg.de would be.

In T216886#5056221, @Framawiki wrote:

In T216886#5056126, @Zoranzoki21 wrote:

Ok, so I will add only uni-hamburg.de

Thanks much!

As said previously note that exact uni-hamburg.de entry will not wok as excepted. mmp.sub.uni-hamburg.de would be.

Ok, will be done as you said.

Change 500154 had a related patch set uploaded (by Zoranzoki21; owner: Zoranzoki21):
[operations/mediawiki-config@master] Add three domains at wgCopyUploadDomains

https://gerrit.wikimedia.org/r/500154

Change 500154 merged by jenkins-bot:
[operations/mediawiki-config@master] Add three domains at wgCopyUploadDomains

https://gerrit.wikimedia.org/r/500154

Mentioned in SAL (#wikimedia-operations) [2019-04-03T16:22:52Z] <lucaswerkmeister-wmde@deploy1001> Synchronized wmf-config/InitialiseSettings.php: SWAT: [[gerrit:500154|Add three domains at wgCopyUploadDomains (T216886, T219075)]] (duration: 01m 00s)