First, make sure you are using the correct email address. Your email should match that used by the organizer when adding you as a speaker. Second, make sure you're using the latest version of Google Chrome as your web browser to optimize performance.
If you can, move closer to your Internet router.
Turn off your camera on the bottom left corner of your screen to increase connectivity.
Mic and camera issues
Use your computer's built-in audio and microphone.
Make sure to unpair any interfering Bluetooth devices.
Restart your browser. Close your window and re-enter your talk. Reactivate the mic and camera.
Make sure you are not muted by accident.
If you hear an echo from your end:
You have a laptop plugged into a monitor. Use only one computer at a time.
If you work for a government office
Ask your IT professional to set up the network and firewall settings listed here.