At the moment download.opensuse.org is unreachable for me (and also for IsUp.Me -> Check if your website is down or up?).
So what to do if you urgently want to install some software? As described on openSUSE:Mirrors - openSUSE
download.opensuse.org selects the best mirror for you. Well, if it does not respond we have to do it manually.
Go to openSUSE Download Mirrors - Overview (luckily that seems to use different infrastructure and it is
reachable now) and pick a suitable mirror.
The URL can be changed in yast → software → software repositories for the repo you need.
Note that the URL on the mirrors can be longer than on download.opensuse.org. I used the /distribution/ part
of the URL to “synchronize”
And maybe it might be a good idea to revert the change when download.opensuse.org is up again. Mirrors might
change in the future.