I've noticed that the external communities I'm subscribed to aren't syncing. I checked a few on their home server (lemmy. world), and they've got plenty of new posts (eg. !news@lemmy.world), but the posts aren't showing up here. I don't think it's just me, but I've been wrong before. Anybody else?
It seems that something went wrong with our nameserver, thus no connections to the 'outside world' were working. As soon as I added a new nameserver, federation started working again (this also affected server updates).