Proxy Timeout: ERR_CONNECTION_TIMED_OUT and 504 Gateway Timeout

What the error means

A timeout is not a refusal but silence: the program waited for a response longer than it is willing to and aborted the request. In a browser it is ERR_CONNECTION_TIMED_OUT or ERR_TIMED_OUT, in programs it is “connection timed out”, and at an intermediary it is 504 Gateway Timeout.

A request through a proxy passes three legs: from you to the gateway, from the gateway to the exit address, and from there to the site. Any of them can slow down.

Causes

• A slow exit address. Residential and mobile addresses are ordinary devices on home and mobile internet; their speed varies.
• The site responds slowly or does not respond. Overload, maintenance or a deliberate delay for suspicious requests.
• The timeout in the program is too short. Three to five seconds is often not enough for a request through a residential address.
• The connection to the gateway is closed in your network. A firewall silently drops packets to the required port.
• A heavy page. Large files and pages with hundreds of resources take longer to load than the limit.

How to fix it

1. Retry the request: with rotation, it will go through a different address.
2. Increase the timeout in the program to 30–60 seconds.
3. On a sticky IP, change the session — take another port from the 10000–20000 range.
4. Check the site without the proxy: if it is slow that way too, the site is the cause.
5. If speed and stability matter, try datacenter proxies: their addresses are hosted in data centers.
6. Check that the proxy port is not closed in your network: try another network.

How to check that it works

The proxy checker shows the response time. If the address responds quickly there but the program gets timeouts, increase the timeout or look for the cause on the site's side.