Zoom Error 103033 | How to Fix

The Zoom Error Code 103033 is primarily a connectivity issue that prevents your Zoom client from establishing or maintaining a connection with the Zoom servers.

It typically occurs when you are:

• Trying to join or start a meeting.

• Suddenly dropped from an active meeting.

• Moving into or between Breakout Rooms.

🛠️ How to Fix Zoom Error 103033

Since this is usually a network or security issue, here are the most effective troubleshooting steps:

1. Check Your Internet Connection

• Restart your Router/Modem: Unplug your modem and router for about 30 seconds, then plug them back in. This resolves many temporary network errors.

• Test Your Connection: Try accessing other websites or streaming services to confirm your internet is working properly and is stable.

• Switch Connections: If possible, try switching from Wi-Fi to a wired (Ethernet) connection, or switch to your phone’s mobile hotspot to see if the error goes away.

Also Read : AT&T 16 Digit Network Unlock Code

2. Check Security and Firewall Settings

This is the most common root cause for this specific error code.

• Check Firewall/Antivirus: Your computer’s firewall (like Windows Defender) or your Antivirus software may be blocking the Zoom app from connecting.

  • Temporarily disable your Antivirus/Firewall and try joining the meeting again. If it works, you need to add Zoom as an exception in your security software settings.

• Check Proxy (If applicable): If you are on a corporate, school, or business network that uses a proxy server, contact your network administrator to ensure the correct Zoom domains and ports are whitelisted.

3. Restart and Reinstall Zoom

• Restart Zoom: Completely close the Zoom application (make sure it’s not just minimized to the system tray), wait a minute, and relaunch it.

• Reinstall Zoom: If the issue persists, the Zoom application itself might be corrupted:

  1. Uninstall the Zoom client completely from your computer.

  2. Download the latest version directly from the Zoom Download Center.

  3. Install the new version and try joining the meeting again.

4. Check Meeting-Specific Permissions (Less Common)

In some rare cases, especially with registration-required webinars, this error can appear if your email has been denied or unapproved by the meeting host.

• Contact the Meeting Host: If the above steps fail, reach out to the meeting organizer and confirm that your email address is approved to attend the specific meeting.

🌐 Network Firewall and Proxy Requirements

The Zoom client relies on specific TCP and UDP ports to connect and maintain audio/video sessions. The minimal required configurations are:

The error code 103033 in Zoom is typically caused by network connectivity issues, often related to firewall or proxy settings that block communication with Zoom’s servers.

Since you confirmed that you need the specific network requirements for whitelisting, here are the essential ports and domains you or your network administrator need to allow in your firewall or proxy server to ensure a stable connection:

🌐 Network Firewall and Proxy Requirements

The Zoom client relies on specific TCP and UDP ports to connect and maintain audio/video sessions. The minimal required configurations are:

Domain Whitelisting

If your firewall or proxy server filters by domain name, you must ensure that all traffic to the following domains is allowed (and preferably excluded from SSL inspection):

• *.zoom.us

• *.zoom.com

💡 Important Note on IP Addresses

Zoom’s cloud is massive and global, meaning its IP address ranges change frequently.

Instead of trying to whitelist all possible IP addresses (which are hundreds and are constantly updated), Zoom strongly recommends that network administrators whitelist the domains above and allow traffic on the specified ports. This ensures that the Zoom client can always connect to the correct server nearest to you.

If you are on a personal network (at home) and received this error, it is likely your antivirus or computer’s native firewall (like Windows Defender or macOS firewall) is blocking the Zoom Application itself. The quickest fix is to ensure the Zoom Video Conference app is explicitly allowed access for both Private and Public networks.