Please note that Clamav have updated some of their backend stuff for delivering database updates.
Seems it is currently in a bit of a pickle....
e.g
http://lists.clamav.net/pipermail/clamav-users/2018-June/006350.html Team --
Today we were able to add 100% of the mirror infrastructure to our CDN, Cloudflare. We are currently measuring the load and evaluating the viability and problems (if any) with this solution. We are currently pushing approx 12GB a second through their Tier 1 POP locations.
We are seeking feedback about the stability of this, or if any updates are failing. (I have seen the thread that is currently on-going).
If you having problems downloading from the ClamAV mirror infrastructure, please delete your mirrors.dat file and start over.
--
Joel Esler
Sr. Manager
Open Source, Design, Web, and Education
Talos Group
http://lists.clamav.net/pipermail/clamav-users/2018-June/006340.html