“The proxy server is not responding”, followed by a probable cause of the error and a couple of tips to fix it, is an error message that appears when a user affected by it tries to access the Internet through an Internet browser such as Internet. Explorer, Google Chrome o Mozilla Firefox.
In many cases, if an affected user has two or more browsers installed on their computer, find that one of your internet browsers works perfectly fine. The error message “The proxy server is not responding” indicates that the proxy server a person is using is not responding to requests from their computer, and this is alarming for many users affected by this problem because most of them do not even use a proxy server to begin with!!
In most cases, the error “The proxy server is not responding” is simply due to some errors or problems in the registry and can be easily fixed. However, a suspicious or malicious program can also cause a harder-to-treat version of this problem, I'll talk about later. The first is the first, if you see the error “The proxy server is not responding” every time you try to access the internet with a browser, follow the steps below to solve the problem:
Check internet properties
Hold down the Windows key and press R. Type inetcpl.cpl and click OK.
Go to the Connections tab and choose LAN Settings. Make sure the option “Use a proxy server for your LAN” is not checked. If it's checked, uncheck it, click ok / Apply and Accept.
Once this is done, restart the PC and the TEST. If it still doesn't work, go to the Registry Editor Method below.
Change proxy settings through registry editor
It is important to back up your registry settings before modifying them. Hold down the Windows key and press R. Type regedit in the run dialog and click OK. To back up the registry, after opening it, click File -> To export, name the log file, for example. for example: backupreg and click Save. To import / restore from backup, open registry editor again, click File -> Import and select the file that you have previously exported, what is your backup. Once the backup is done; Navigate to the following route:
Computer HKEY_CURRENT_USERN-SoftwareN-MicrosoftWindowsNCurrent versionNInternet settings
In the right panel, look for the string ProxyEnable. Right click on it and choose Delete. If there is a ProxyServer string, Migrate Proxy y Proxy Override, right click on it and delete it too.
Now restart the PC and try. If it still doesn't respond, continue with the next steps.
Restart your web browsers
If it is on Windows 10 and usa Edge, follow the steps here to reset the edge; otherwise, choose the browser tab you are using.
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Restart Internet Explorer.
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Reinicia Google Chrome
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Reinicie Mozilla Firefox
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More
To restart Internet Explorer, hold down the Windows key and press R.
This will open the run dialog, in run dialog type inetcpl.cpl and go to Advanced tab; from the Advanced tab; Choose Reset, check Delete personal settings and then hit the Reset button again. This will not erase your bookmarks, BUT you will have to recover them by doing CTRL + SHIFT + B or by going to the bookmarks menu
Google Chrome restart is generally unsuccessful, so what i would recommend is creating a new chrome profile. Before doing it, backup your bookmarks so you can import them later. Check out this guide to import / export Chrome bookmarks.
Google Chrome salt in full.
Enter the Windows key from the keyboard shortcut 
+ R to open the run dialog.
In the dialog window that appears, type the following in the address bar.
Windows Vista / Windows 7 / Windows 8 / Windows 10 / Windows 10:% LOCALAPPDATA% NGoogleNChromeN user data
Look for the folder called “Predetermined” in the directory window that opens and rename it “Default backup”.
Try to open Google Chrome again. A new folder will be created automatically “Default” when you start using the browser.
In the Firefox address bar; to write about: support for and choose Update Firefox; and then Update Firefox again.
Click here to see the steps to reset the edge
If after restarting the browsers it starts working, most likely due to adware that needs to be removed to prevent it from reappearing. To do this, you can use AdwCleaner (google it) to download and install it, and then clean the adware. However, if it still shows that the proxy server is not responding to the error, do a full scan with your antivirus software and remove any threats you find, if it still doesn't work, uninstall antivirus / malware y vpn, or other security software temporarily to test it. If then it works, you can reset your security program, in doing so, the rules configured in the firewall will be reset / antivirus, etc.
Also check that Windows could not automatically detect the proxy settings for this network
