I'm pretty sure you already noticed by now, but our default mirror is down since Saturday, 20th of January 2018. And since we are yet to enable the new mirror configuration file on 28th of January 2018, switching to another mirror requires manual intervention.
emerge -av1 --nodeps sisyphus
After the steps above, sisyphus will use the new mirror and everything will work as it should.
We are sorry for inconvenience, we've been informed the mirror will be back online once the server maintenance will be finished.