What to do when Chrome suggests checking the proxy and the firewall

Updated: 2026-11-07

"Checking the proxy and the firewall" is one of the hints Chrome lists on Windows when a page fails to load, usually next to "Running Windows Network Diagnostics". It is a suggestion, not an error code, and it does not say what is actually wrong. Below is the order we would inspect things in, from the most frequent culprit to the least.

Proxies with a support desk behind them

View pricing Free Proxy Checker

Five suspects, in order of likelihood

Suspect	Why it breaks pages
Windows proxy setting	A proxy left switched on after an order ended or an app was uninstalled. Chrome and Edge both read it, so every site fails.
WinHTTP proxy	A separate system-level configuration used by some apps and services. It never appears on the Settings page.
Windows Firewall or antivirus	Either can block Chrome itself, or block outgoing traffic to the proxy's port.
Active VPN	Takes over routing, so the proxy no longer behaves the way you configured it.
Work or campus network	The network's own firewall may drop the proxy port before traffic ever leaves the building.

Step one: the two Windows proxy settings

Go to Settings > Network & Internet > Proxy. Not using a proxy? Switch off the manual proxy setup, and also Use setup script if it is enabled. Using one on purpose? Compare the IP and port there, digit by digit, with the order in your dashboard. The Windows proxy setup page and the turn off proxy guide show the screens.

Then open Command Prompt and type netsh winhttp show proxy. An entry you do not recognise can be cleared with netsh winhttp reset proxy, run from an administrator prompt, which puts WinHTTP back on a direct connection.

Step two: firewall and security software

In Windows Security > Firewall & network protection > Allow an app through firewall, make sure Chrome is ticked for the network type you are on (private or public). Many third-party antivirus products bring their own firewall or web filter. Pause that protection for a few minutes, retest, and switch it back on whatever the outcome.

Firewalls block in one of two ways: they reject a connection immediately, or they discard the packets and let you wait. Those two behaviours leave different traces, which is how you work out where the block sits.

Step three: read the symptom

These outputs were recorded on our test proxy; 203.0.113.10:8080 is a documentation address. One quick experiment settles most cases: share your phone's mobile data with the laptop and try again. If everything works on mobile data but not on the usual network, that network or its firewall is responsible, not the PC and not the proxy.

Instant failure. The checker says connect failed and curl prints curl: (7) Failed to connect to 203.0.113.10 port 8080 after 0 ms: Couldn't connect to server. Nothing accepted the connection. Continue with ERR_PROXY_CONNECTION_FAILED.
Long wait, then failure. The checker says timeout, curl prints curl: (28) Proxy CONNECT aborted due to timeout and Chrome shows ERR_TIMED_OUT. Packets are probably being dropped along the way. Continue with proxy timeout.
Login rejected. The checker says auth failed (407). Your network and firewall are fine; only the credentials are wrong. Continue with the 407 guide.

Step by step

1
Fix or disable the Windows proxy
In Settings > Network & Internet > Proxy, turn off a proxy you do not use, or correct the IP and port of the one you do.
2
Check WinHTTP
Run netsh winhttp show proxy. If an unknown proxy is listed, run netsh winhttp reset proxy as administrator.
3
Let Chrome through the firewall
Open Windows Security > Firewall & network protection > Allow an app through firewall and tick Chrome.
4
Repeat the test on mobile data
Tether to your phone and paste the proxy line into the proxy checker to compare the two networks.
5
Run Windows Network Diagnostics last
If nothing above helped, let the Windows troubleshooter inspect the network adapter and DNS.

Frequently asked questions

What does Chrome mean by checking the proxy and the firewall?

It is a generic hint shown when a page cannot load: confirm the computer is not routed through a wrong proxy and that no firewall is stopping the browser.

Are the steps different on Windows 10 and Windows 11?

The location is identical: Settings > Network & Internet > Proxy. Windows 11 opens the manual proxy section with a Set up button, while Windows 10 uses a switch.

Can I just leave the firewall off?

No. Turn it off only long enough to test. Then switch it back on and add an exception for the app that needs access.

Windows Network Diagnostics says everything is fine. What now?

The troubleshooter often misses a wrong proxy. Inspect the Windows proxy and WinHTTP by hand as described above.

Pages only fail when my paid proxy is switched on.

Test the line in the checker. If the checker connects, the problem is in your device settings. If it fails there too, open a support ticket and include the result.