Firewall blocking Zoom? Introducing confirmation and setting methods

Firewall blocking Zoom  Introducing confirmation and setting methods

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*Zoom and services including the name Zoom are services provided by Zoom Video Communications, Inc.

From July 15, 2022, Zoom will have a 40-minute limit even for meetings with two participants if you have a free subscription. (Previously, it was only for meetings with 3 or more people.)
Companies and organizations using Zoom for business should consider switching to a paid license at this opportunity. Recently, but suddenly I can’t use Zoom! There’s no problem with the app or my account, so why?” In such cases, network security may be the cause.

If you can connect to the Internet but only Zoom cannot connect, your security software or firewall may be blocking Zoom.

If you get a network-related error on Zoom

  • An unexpected error occurred in your meeting. Error code: 5003
  • Network error. Please try again.
  • Unable to connect to our service. Please check your network connection and try again.

When Zoom gets stuck in “connecting” or times out, you may get an error message like the one above.

From these messages, you can see that there seems to be some problem with the network connection.

Check network connection status

First, make sure your device is connected to the network.

Open your browser and try to browse the website.

If you can connect to the website and the page loads quickly, then the issue is more likely a security setting than your network connection.

Examine the error code to determine the cause

Any indication of an error code will help identify the cause.

Check the Zoom error code/message on the Zoom support site (

The error codes for cases where the connection does not progress or times out from “connecting” are roughly divided into the following cases.

  • 5000 series such as “5003” “5004”
  • 104100 series such as “104101”, “104113”

These are errors when there is a problem connecting to the Zoom server, and are caused by firewalls, proxies, or antivirus software blocking connections to Zoom.

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Roles of firewalls, proxy servers, and security software

Roles of firewalls, proxy servers, and security software

Firewalls, proxy servers, security software…

You’ve heard of it, but you might not have much idea what it’s like.

First, let’s take a look at each role.

What is a firewall

A firewall is a “firewall” that prevents unauthorized access and cyberattacks. Parse the communication to decide whether to pass it through.

There are two types of firewalls:

personal firewall

A firewall installed on client PCs that is effective in preventing virus intrusion and protecting against unauthorized access.

Filters incoming and outgoing packets by IP address and port number to determine whether to allow communication.

Windows Defender”, which is standard installed on Windows 10 computers, is also classified as a personal firewall.

network firewall

A firewall installed between an external network and an internal LAN in a company, etc.

There are “packet filtering type” that filters communication by packet, “application gateway type” that controls each application protocol such as HTTP and FTP, and “circuit level gateway type” that even specifies and controls ports.

What is a proxy server

A “proxy server” is a server that connects to the Internet instead of a personal computer, and has been widely used in companies.

Since the computer does not directly connect to the Internet, but passes through a proxy server, it is difficult to identify the access source.

It is also possible to obtain access logs from client PCs and speed up site display by using the proxy server cache, which is effective for appropriately managing the use of PCs as an organization.

One of the functions of a proxy server is filtering, which restricts access to specific sites, and is used for purposes such as preventing access to illegal sites or sites that violate public order and morals.

What is security software (antivirus software)?

All software that aims to prevent malware intrusion, prevent unauthorized access, protect information, etc., is called “security software.”

Antivirus software such as “Virus Buster” “ESET” “Norton” comes to mind when you hear security software.

In addition to checking the Internet connection and email attachments to detect viruses, there is also a function to scan connected external media to check if it contains malware, so it is a countermeasure against malware that invades from various routes. is possible.

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In addition to antivirus, security software also includes spam mail block, device search, and online payment protection.

If Zoom is blocked by the firewall

If Zoom is blocked by the firewall

We will introduce troubleshooting when Zoom is blocked by a firewall and cannot connect.

Restart the Zoom app/device

Many of the malfunctions in the operation of the computer and applications can be improved by restarting.

If there is a problem with the Zoom connection, before checking the firewall settings, try restarting the Zoom app and restarting the device, which are easy to do.

Quit app from background process

The Zoom app is running in the background even after you click the “x” to close it.

To completely exit the app, please exit from the background process.

  1. Press “Ctrl” + “Alt” + “Delete” at the same time to launch “Task Manager”.
  2. Select Zoom from “Background processes” and click “End task”.

Check Zoom failure status

Let’s check if there are any problems with the entire Zoom service.

You can check the current outage status at Zoom Service Status (

If the status is “Operational”, no failure has occurred.

Temporarily disable firewall/security software

To find out if the firewall is the cause, temporarily disable the firewall, then connect to Zoom and try isolating it.

The procedure for disabling Windows Defender, which comes standard with Windows 10, will be explained as an example.

  1. Click Start and click Settings (gear icon).
  2. Click Update & Security.
  3. Click Windows Security.
  4. Click Virus and threat protection.
  5. Click Manage Settings.
  6. Turning off Real-time protection will disable Defender.

If you are using other security software, the above operations may not be possible.

In that case, please try suspending the protection according to the operation method of each security software.

Dangerous if left disabled!

If you can connect to Zoom by disabling the firewall, it may be because the firewall is blocking it, but it is not desirable for security to keep the firewall disabled all the time.

If you can identify the firewall as the cause, remove Zoom from the firewall check using the “exception settings” method described below.

Set Zoom as a Firewall Exception

If a specific app is blocked by the firewall, you can remove it from the firewall check and it will not be caught.

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If you are sure the app is safe, try setting it as a firewall exception.

I will show you how to set it up in Windows Defender.

  1. Open Control Panel.
  2. Click “Category” and “System and Security” for the display method.
  3. Click “Allow an application through Windows Firewall” under “Windows Defender Firewall”.
  4. Click Change Settings.
  5. Click “Allow another app”.
  6. Click Browse, select Zoom.exe, and click Add.
  7. Zoom has been added to “Allowed apps”. Check “Private” and “Public” and click “OK”.

For company personal computers and networks

You can set up a personal firewall on your computer, but your administrator sets up firewall and proxy server rules for your company’s network.

Unauthorized users cannot see or change the settings, so please check with your administrator.


  • If you cannot connect to Zoom with a “5003” error, etc., it may be blocked by a firewall.
  • Isolate by temporarily disabling firewalls and security software
  • Disabling protection is dangerous. If you add Zoom to the exception settings, it will not be blocked
  • Consult your administrator for firewall and proxy server settings for your company’s network.

Firewalls are essential to keeping your computer safe from danger, but they can sometimes block even safe connections.

Take advantage of firewall exceptions to use Zoom Meetings in a secure environment.