solution 1
Change database.clamav.net by db.local.clamav.net
you can also use one of the following mirror
https://www.clamav.net/mirrors.html
solution 2
download and extract
https://downloads.sourceforge.net/gnuwin32/wget-1.11.4-1-bin.zip
and
https://downloads.sourceforge.net/gnuwin32/wget-1.11.4-1-dep.zip
copy file wget.exe libeay32.dll libiconv2.dll libintl3.dll libssl32.dll
in C:\Windows
create file ClamWin\bin\freshclam.bat
@echo off
rem you can change the mirror or create your own mirror
set mirrordatabase=db.local.clamav.net
echo delete %3\bytecode.cvd
del %3\bytecode.cvd
echo ...
echo delete %3\daily.cvd
del %3\daily.cvd
echo ...
echo delete %3\main.cvd
del %3\main.cvd
echo ...
echo download http://%mirrordatabase%/bytecode.cvd
echo ...
echo Please Wait
wget http://%mirrordatabase%/bytecode.cvd -P %3
echo ...
echo download http://%mirrordatabase%/daily.cvd
echo ...
echo Please Wait
wget http://%mirrordatabase%/daily.cvd -P %3
echo ...
echo download http://%mirrordatabase%/main.cvd
echo ...
echo Please Wait
wget http://%mirrordatabase%/main.cvd -P %3
exit |
in ClamWin Click Tools/Preferences
Click file Locations
change freshclam.exe in freshclam.bat
enjoy