This should be related to your bandwidth.
If you are an IT admin, it is suggested to use Network Planner to assess your network including bandwidth calculations and network requirements across your organization's physical locations. When you provide your network details and Teams usage, the Network Planner calculates your network requirements for deploying Teams and cloud voice across your organization's physical locations.
You can learn from this article about how to use the Network planner for Microsoft Teams. Please pay attention to Build your plan and Create a report parts.
Besides, there are some tasks can help you to optimize your network. You can read the Network optimization section in this document.
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