[squid-users] how to get rid of IPv6 caused messages ...

Hello,

the router from ISP has IPv6 disabled; my public IP is only IPv4;

I get regularily a message like this:

ERROR
The requested URL could not be retrieved
------------------------------------------------------------------------
While trying to retrieve the URL:http://www.google.com/firefox?
<http://www.google.de/firefox?>
The following error was encountered:

     * *Connection to 2a00:1450:4001:80b::1017 Failed *

The system returned:
/(101) Network is unreachable/
The remote host or network may be down. Please try the request again.
Your cache administrator is my-email.
------------------------------------------------------------------------
Generated Fri, 28 Feb 2014 13:03:40 GMT by myproxy-host (squid/3.3.11)

my squid is running on CentOS 6.5 64-bit;

I already have the following in squid.conf

tcp_outgoing_address myproxy-host's IPv4-address all
and
dns_v4_first on

Thanks for help,
Walter