I have a http proxy in a VM in our private network. I want to proxy all our network traffic to this http proxy. How can I do it in private network?

We try to apply a Destination NAT (DST_NAT) on our Microtik router with this config:

add action=dst-nat chain=dstnat dst-address-list=!Private 
    protocol=tcp src-address=192.168.1.0/24 to-addresses=10.111.10.100 
    to-ports=24240

But when we try to connect to network we get:

Secure Connection Failed

An error occurred during a connection to www.google.com. PR_END_OF_FILE_ERROR

Error code: PR_END_OF_FILE_ERROR

    The page you are trying to view cannot be shown because the authenticity of the received data could not be verified.
    Please contact the website owners to inform them of this problem.

What is wrong? I know that I can connect to it with curl command like this:

curl -x "http://10.111.10.100:24240" google.com

I try to proxy all private network to a http proxy. I expect to proxy the traffic successfully.