Dear John Peter1,
Good day! Thank you for posting to Microsoft Community. We are happy to help you.
To bypass proxy servers for Microsoft Teams, consider the following options.
Ensure your proxy settings are configured to allow Teams to connect directly. This might involve updating your PAC file or firewall rules to bypass the proxy for Teams traffic. Put Teams Phones and Meeting Room devices on their own VLAN and provide them with direct Internet access. If bypassing the proxy is not an option, refer to the documentation for configuring proxy servers for Skype for Business Online. Refer to Managing Microsoft 365 endpoints - Microsoft 365 Enterprise | Microsoft Learn.
If you’re using a VPN, consider setting up a split tunnel for Teams traffic. This allows Teams traffic to bypass the VPN and connect directly to Microsoft’s servers. Microsoft recommends that Teams traffic bypasses proxy server infrastructure, including SSL inspection. You might achieve this by putting Teams devices on their own VLAN and providing them with direct Internet access. Refer to Proxy servers for Teams or Skype for Business Online - Microsoft Teams | Microsoft Learn.
If bypassing the proxy is not an option, ensure your proxy server is configured correctly. Some proxy server vendors offer automated configuration based on Microsoft 365 IP Address and URL Web Service data. Hence, you'll need to allow specific URLs on your network,Allow the Azure portal URLs on your firewall or proxy server - Azure portal | Microsoft Learn.
If there anything else you’d like to know or any specific detail, please let me know and we can explore other options. Please note that our initial response does not always resolve the issue immediately. However, with your help and more detailed information, we can work together to find a solution. Thank you for your help.