Proxy Ser 2 Clint 10061 Con Refused Erro

Hello All. Maybe you can help with some errors i am receiving occasionally on my Client that use a proxy Server to connect to the internet.

We are getting 10061 Connection Refused errors on the clients. The Proxy Server is hosting 2 web sites and is reverse proxing for one internal site. Some Client have proxy client install some are just pointing through IE to the proxy. Can’t seem to find the fix for these errors