It seems that lang.moodle.org is down
And it's not (already?) seen from Moodle sites status page.
lang.moodle.org is down for scheduled maintenance. David posted yesterday on the site:
Just to let you know that we will need to perform a regular maintenance on the AMOS site lang.moodle.org to make it ready for the Moodle 3.9 development cycle. The server will go into a maintenance mode, starting today 10 December 2019 at 17:00 UTC. We expect it to get back online tomorrow. Thank you for understanding.