Anyone who works with proxies long enough eventually bumps into the same confusing issues, tests fail for no clear reason, good IPs look “dead,” or a checker says something is wrong even though the proxy works fine in your tool.
Most of these problems come down to simple mistakes made during the test, not the proxy itself.
In this article, we’ll walk you through the errors people run into the most and how to fix them.
Before You Start – What a Proper Proxy Check Should Verify
Before you even dig into specific errors, it helps to know what a clean, proper proxy check is supposed to confirm. A good ip proxy checker doesn’t just say “working” or “not working.”
It should tell you whether the proxy can connect, how fast it responds, if it leaks your real IP, and whether the location actually matches what you need.
When you know what the checker should be verifying, it’s much easier to spot what went wrong and why a proxy looks bad even though it might still be usable.
Error #1 — Testing With the Wrong Protocol (HTTP vs. SOCKS)
Testing a proxy with the wrong protocol is one of the most easily made errors. SOCKS and HTTP proxies do not act in the same manner and when loaded into the checker with the incorrect type, they will fail, though they may work flawlessly in actual use.
SOCKS proxies can support a wider variety of traffic and connect at a lower level, whereas HTTP proxies are specifically designed to support web requests. Confuse them, and the checker will not know what you are testing.
Always set the proxy format to the testing protocol to ensure you do not set good IPs to be marked as dead without any reason.
Error #2 — Ignoring Authentication (User/Pass, IP Allowlist)
The other problem is forgetting that not all proxies will work before you log in correctly. Two methods are typically provided by the providers, including username/password or IP allowlisting.
Failure to do this will cause the proxy checker to just deny the connection and you will be left assuming the proxy is broken when it is actually blocked on your side.
It is important to verify that the login details are correct or that the IP of your device is included in the allowlist before running any test. There is a shocking number of unusable proxies that do work when the authentication is configured correctly.
Error #3 — DNS & WebRTC Leaks That Reveal Your Real IP
A proxy might appear to be a good one, but might still reveal your actual IP address in DNS or WebRTC. This occurs frequently when the checker just checks the basic connectivity and not the inner aspects of the connection.
In the event of DNS leaks, your computer will make requests not through the proxy and there are still sites where the origin of your request will be visible. Browsers are no different, and WebRTC leaks can reveal your true IP address despite the proxy being enabled.
Always perform a DNS and WebRTC test, provided your checker supports it. A quick way to be sure that the proxy is completely hiding you, rather than giving you an illusion of privacy.
Error #4 — Geolocation Mismatch (Country/City Doesn’t Match Target)
A proxy might connect without any problems, but the location can still be completely wrong. This happens more often with cheap pools or recycled IPs where the geo data hasn’t been updated.
You think you’re testing a German proxy, and suddenly it shows up as France or Poland. For scraping, ad checking, or anything that relies on local accuracy, this throws your whole setup off.
Always check the country and city before using a proxy for location-specific tasks. If the IP doesn’t match what the provider listed, remove it from your batch, wrong placement will give you unreliable results no matter how fast the proxy is.
Error #5 — Over-Rotating or Under-Rotating Endpoints
Rotation settings can break a proxy test without you realizing it. If the proxy rotates too fast, the checker might hit a new IP on every request, which makes the results look unstable even though the proxies themselves are fine.
On the other hand, if rotation is too slow, you may get stuck on a single bad IP and think the entire batch is failing.
Getting rotation right is all about balance. For scraping, a steady rotation usually works best. For account-based tasks, a fixed or slow-rotating IP is safer. If your results look strange or inconsistent, check your rotation settings before assuming the proxies are bad.
Error #6 — Conflating Residential, ISP, and Datacenter Proxies
A lot of proxy checking issues come from treating every proxy type the same. Residential, ISP, and datacenter proxies behave differently, so their test results won’t look identical.
Residential and ISP proxies usually pass more location and block tests but respond a bit slower because they come from real devices or ISP networks.
Datacenter proxies are much faster, but strict websites flag them more often, so they can show more failures in your checker even when they’re still usable for lighter scraping.
If you mix all three types into one test and judge them by the same standards, you’ll end up thinking the datacenter proxies are “bad” or the residential ones are “slow.”
Test them separately and expect different results, that’s how you get an accurate read instead of throwing out good IPs.
