Getting ERR_PROXY_CONNECTION_FAILED? Here’s why it happens and the exact fix.
You are seeing ERR_PROXY_CONNECTION_FAILED because your client cannot establish a TCP connection to the proxy gateway. The fix: check your proxy endpoint address, port, and ensure your firewall allows outbound connections on the proxy port.
Check gw.knoxproxy.com:7000 for residential and dc.knoxproxy.com:8000 for datacenter against your dashboard.
Run: telnet gw.knoxproxy.com 7000. If it connects, the network path is clear.
Run: nslookup gw.knoxproxy.com. Verify it resolves to an IP address.
Allow outbound TCP on ports 7000 and 8000 to gw.knoxproxy.com and dc.knoxproxy.com.
import requests
# Correct port: 7000 for residential gateway
proxy = "http://USER:PASS@gw.knoxproxy.com:7000"
r = requests.get("https://httpbin.org/ip", proxies={"https": proxy})
print(r.json()) # {"origin": "residential-ip"}Test your setup with our proxy checker, then contact support if ERR_PROXY_CONNECTION_FAILED still won’t clear.
ERR_PROXY_CONNECTION_FAILED means your HTTP client attempted to connect to the proxy server but the TCP handshake failed. The request never left your machine. This is a local network or configuration issue -- the proxy gateway is unreachable from your client. Common in corporate networks with restrictive firewalls, misconfigured proxy URLs, or when using the wrong port.
Use the exact endpoint from your dashboard: gw.knoxproxy.com:7000 for residential, dc.knoxproxy.com:8000 for datacenter.
Allow outbound TCP to gw.knoxproxy.com on ports 7000 and 8000 in your firewall rules.
Check your DNS configuration. Try using 8.8.8.8 or 1.1.1.1 as DNS resolvers.
If connectivity tests pass but your application still fails, the issue may be in your HTTP library proxy configuration. Contact KnoxProxy support with your library/language and proxy URL format.
From your machine, not the proxy or the target server. ERR_PROXY_CONNECTION_FAILED means your client's TCP handshake to the proxy gateway itself failed before any request was sent. The proxy server never even received your request, so check your endpoint address, port number, and local firewall rules first.
Your server likely runs behind a stricter firewall than your laptop, one that blocks outbound connections on non-standard ports like 7000 and 8000. Add explicit firewall allow rules for those proxy gateway ports, or ask your hosting provider or infrastructure team to whitelist them for your account.
No. KnoxProxy gateway ports are fixed and cannot be changed: 7000 for residential, 8000 for datacenter, and 9000 for ISP proxies. You cannot configure custom ports on your end. Make sure your firewall explicitly allows outbound traffic on whichever of these ports your plan uses.
KnoxProxy comes pre-configured to avoid the most common errors. Get started and fix ERR_PROXY_CONNECTION_FAILED for good.