How to Fix Zoom "Error Code 104103" — Can't Connect to Our Service

By FixMyError · Updated October 17, 2026 · 7 min read

What "Error 104103" means

You click a meeting link, Zoom opens, and instead of the waiting room you get "Can't connect to our service, please check your network connection and try again. Error code: 104103." It feels like an internet problem — and sometimes it is — but according to Zoom's own support documentation, this error most often means the connection between your device and Zoom's servers is being blocked by something on your side: a firewall, a proxy server, antivirus software, or simply an outdated version of the Zoom app failing the server handshake.

That distinction matters because it changes the fix. If your internet were truly down, nothing would load — but most people hitting 104103 can browse the web just fine. The real task is finding out what is silently intercepting Zoom's traffic. Corporate and school networks are famous for this: their firewalls whitelist only approved apps, and Zoom sometimes isn't on the list. Home users hit it too, usually because of an overzealous antivirus suite, a leftover proxy setting from a previous VPN, or an app version that's months behind. The fixes below are ordered from quickest to most thorough, and step 1 includes a simple test that tells you within minutes whether the problem is your network or your device.

Common causes

• Unstable or restricted network: weak Wi-Fi, a router that needs restarting, or a school/office network that filters traffic can all cut Zoom off from its servers.
• VPN or proxy intercepting traffic: an active VPN or a leftover proxy setting reroutes Zoom's connection, and many of them block the ports Zoom needs.
• Firewall blocking Zoom: Windows Defender Firewall or macOS firewall can silently block Zoom — especially after a fresh install that was never granted an exception.
• Antivirus software interference: security suites with web shields or network filtering sometimes treat Zoom's encrypted traffic as suspicious and drop it.
• Outdated or corrupted Zoom app: an old app version can fail the connection handshake with Zoom's current servers, and corrupted cache files can break it entirely.

How to fix "Error 104103" — step by step

Work through these fixes in order. Step 1 includes a quick test that narrows the problem to your network or your device, so don't skip it.

1. Verify your internet connection and restart your network gear. Open a browser and load a few pages to confirm the connection itself works — error 104103 often appears when the web is fine but Zoom specifically can't connect. Unplug your modem and router from power, wait a full 60 seconds, plug them back in, and wait for all the indicator lights to stabilize before testing again. Here is the key diagnostic: if you have a phone, turn on its mobile hotspot and connect your computer to it, then try joining the meeting. If Zoom works on the hotspot, your main network is the problem — look at the router's firewall, parental controls, or any ISP-level filtering. If the hotspot fails too, the problem is on the device itself, and the steps below will sort it out.
2. Update Zoom to the latest version. An outdated app can fail the server handshake and trigger error 104103 even when your network is perfect. On the desktop app, click your profile picture in the top-right corner and choose "Check for Updates," then install whatever version it finds — Zoom updates frequently, so even a version that's a few weeks old can matter. On Android, open the Google Play Store, search for Zoom, and tap Update if the button is available. On iPhone, open the App Store, tap your profile icon at the top, scroll to the available updates, and update Zoom. After updating, close Zoom completely and reopen it before trying the meeting again.
3. Turn off your VPN and proxy temporarily. VPNs and proxies are among the most common causes of error 104103, because many of them block the TCP and SSL connections Zoom relies on. Disconnect any VPN app you have running — and check for ones you forgot, like a browser extension or a corporate profile that auto-connects. On Windows, go to Settings, then Network & internet, then Proxy, and switch off "Use a proxy server" under Manual proxy setup. On macOS, open System Settings, then Network, click your active Wi-Fi connection, then Details, then Proxies, and uncheck every protocol in the list. On a phone, go to Settings, then General (iPhone) or Network (Android), then VPN, and disconnect. Try the meeting again — if it connects, you've found the culprit.
4. Allow Zoom through your firewall. Firewalls block apps they don't recognize, and Zoom sometimes never gets its exception — particularly after a fresh install. On Windows, open Control Panel, go to System and Security, then Windows Defender Firewall, and click "Allow an app or feature through Windows Defender Firewall" on the left. Click "Change settings," find Zoom in the list (if it's missing, click "Allow another app" and browse to the Zoom executable), and check both the Private and Public boxes. On macOS, open System Settings, then Network, then Firewall, click Options, and confirm Zoom is listed with "Allow incoming connections." Click OK, restart Zoom, and try joining again.
5. Pause your antivirus briefly and add Zoom as an exception. Security suites with network shields can drop Zoom's encrypted traffic without ever showing you a warning. Open your antivirus and look for an option like "Disable shields for 10 minutes" or "Pause protection." With protection paused, try joining the meeting — if it works, the antivirus was the blocker. Turn your protection back on immediately, then open the antivirus settings, find the exclusions or exceptions list, and add the Zoom app so future meetings aren't interrupted. Don't skip the exception step: leaving your antivirus off is trading your security for one meeting.
6. Reset your network settings and clear Zoom's cache. Stale DNS entries and corrupted cache files can keep the error coming back even after everything else is fixed. On Windows, press Win + R, type cmd, press Enter, then type ipconfig /flushdns and press Enter to clear the DNS cache, then restart your computer. On Android, go to Settings, then Apps, then Zoom, then Storage, and tap Clear Cache (this won't delete your account or meetings). On iPhone, go to Settings, then General, then iPhone Storage, tap Zoom, choose Offload App, then reinstall it from the App Store. As a final fallback, fully uninstall Zoom and download a fresh copy from Zoom's official download page — a corrupted install occasionally needs a clean slate.

Did this fix it? Quick checklist

• You can join a test meeting without the 104103 error
• Zoom is updated to the latest version (no pending update)
• VPN and proxy are turned off (or correctly configured for your network)
• Zoom is allowed through your firewall and antivirus exceptions

If you've done all six steps and error 104103 still appears, the block is probably at the network level — a school or workplace firewall you can't change yourself. Test on a mobile hotspot to confirm: if Zoom works there but not on the institutional network, take the error code to your IT department or network administrator and ask them to allow Zoom's domains and ports through the firewall and proxy. If the hotspot fails too, contact Zoom support with the error code and the steps you've already tried — you've ruled out everything a user can normally control.