Checking the proxy and the firewall: a practical checklist
Updated:
When a page will not load, Chrome on Windows often lists a few things to try, including "Checking the proxy and the firewall" and "Running Windows Network Diagnostics". That is advice, not an error code. This page turns the advice into a concrete checklist, starting with what most often goes wrong.
The order to check things
- 1. The proxy in Windows Settings. Most common: an old proxy still switched on after an order expired or some software was removed. Chrome and Edge read this setting directly.
- 2. The WinHTTP proxy. Some apps and system services use a separate WinHTTP configuration that is not shown on the Settings page.
- 3. Windows Firewall or antivirus. Either can block Chrome specifically, or block outbound connections to the proxy port.
- 4. A running VPN. It can take over traffic routing so the proxy does not behave as you expect.
- 5. An office or school network. The network firewall can block the proxy port outside your machine.
Check the Windows and WinHTTP proxy
Open Settings > Network & Internet > Proxy. If you do not use a proxy, turn off Manual proxy setup, and Use setup script if it is on. If you do, compare IP and port with your dashboard order. Walkthroughs are in Windows proxy setup and the turn off proxy guide.
Next, open Command Prompt and run netsh winhttp show proxy. If it lists a proxy you do not recognise, netsh winhttp reset proxy (run as administrator) returns WinHTTP to a direct connection.
Check the firewall and security software
Go to Windows Security > Firewall & network protection > Allow an app through firewall and confirm Chrome is allowed on the network type you are using. Third-party antivirus suites often run their own firewall; pause web protection for a few minutes to test, then turn it back on.
A firewall can block a connection by rejecting it immediately or by silently dropping packets. The two produce different symptoms, and the output tells you which one you have.
Read the output to locate the block
203.0.113.10:8080 is a documentation address; the outputs were captured on our test proxy. The fastest isolation trick is to tether your laptop to your phone's mobile data and retry. If it works on mobile data and not on the original network, that network or its firewall is the culprit, not your computer and not the proxy.
| You see | Meaning | Read next |
|---|---|---|
Checker: connect failed; curl: curl: (7) Failed to connect to 203.0.113.10 port 8080 after 0 ms: Couldn't connect to server | Refused at once, the port accepts no connections | ERR_PROXY_CONNECTION_FAILED |
Checker: timeout; curl: curl: (28) Proxy CONNECT aborted due to timeout; Chrome: ERR_TIMED_OUT | Nobody answers, packets may be dropped on the way | Proxy timeout |
Checker: auth failed (407) | Network and firewall are fine, only the login is wrong | 407 error |
Step by step
- 1
Switch off or fix the proxy in Settings
Settings > Network & Internet > Proxy: disable an unused proxy or re-enter the correct IP and port.
- 2
Inspect WinHTTP
Run
netsh winhttp show proxy; if an unknown proxy appears, runnetsh winhttp reset proxyas administrator. - 3
Allow Chrome through the firewall
Windows Security > Firewall & network protection > Allow an app through firewall, then check the Chrome entry.
- 4
Test the proxy on another network
Connect through phone data and paste the proxy line into the proxy checker to compare results.
- 5
Run Windows Network Diagnostics if it still fails
Use the Windows network troubleshooter to check the adapter and DNS.
Frequently asked questions
What does "checking the proxy and the firewall" mean?
It is one of Chrome's suggestions when a page fails to load: make sure the device is not using a wrong proxy and that no firewall is blocking the browser.
Is the check different on Windows 10 and 11?
The path Settings > Network & Internet > Proxy is the same. Windows 11 uses a Set up button for the manual section, Windows 10 uses a toggle.
Should I just turn the firewall off?
No. Disable it briefly to test, then turn it back on and add an exception for the specific app.
Network Diagnostics finds nothing but I still cannot connect.
The troubleshooter does not always catch a wrong proxy. Check the proxy and WinHTTP by hand as above.
It only fails when my purchased proxy is on.
Paste the line into the checker. If the checker works, revisit the settings on your device; if it fails too, open a ticket with the result.
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VinaProxy proxies come with Windows setup guides and a support team that looks at failed checks with you.
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