Feed Error: time out

Hello,

I installed this plugin and wanted to add a feed from another site (https://gut.sparkasse-koelnbonn.de/?em_ess=1), but I always get an time out error message…

I already checked if the site with the feed has ESS Feed installed.
I checked the time out ($timeout_sec = 20) in the ESS_Import.php file and even when I change this nothing happens.

I also tried some of the example feeds from the documentation site (ex. https://essfeed.org/feeds/tv_show.ess)…but still I always get the Error Message ?The ESS Feed request timed out with URL“.

Is there something else I could try or maybe I do something wrong? Do I need extra Setting?

Thanks in advance!