I’ve not had trouble updating in the past, but last night:

Querying current.cvd.clamav.net
WARNING: Can't query current.cvd.clamav.net
WARNING: Invalid DNS reply. Falling back to HTTP mode.
If-Modified-Since: Wed, 07 Jun 2017 21:38:10 GMT
Reading CVD header (main.cvd): WARNING: Can't get information about db.US.clamav.net: nodename nor servname provided, or not known
WARNING: Can't read main.cvd header from db.US.clamav.net (IP: )
Trying again in 5 secs…

And

Update failed. Your network may be down or none of the mirrors listed in /opt/local/etc/freshclam.conf is working. Check https://www.clamav.net/documents/official-mirror-faq for possible reasons.

But, when I check the official-mirror-faq I get a 404 error.

What do I need to do to fix this?