[error] [client xx.xx.xx.xx] ap_proxy: trying POST /test/TestService at backend host 'xx.xx.xx.xx/xxxx; got exception 'CONNECTION_REFUSED [os error=0, line 1715 of ../nsapi/URL.cpp]: Error connecting to host xx.xx.xx.xx:xxxx'
You can not eradicate this problem completely. But you can reduce error occurrence. You have to increase the AcceptBacklog for your servers, from the tuning tab. It can be found from:
Environment - Servers - Select server - Configuration - Tuning tab
If you are confused, then click the link for a detailed description.