Since all sessions will take place within the browser environment, is it important to find out wether you're having wifi or application based problems.
Try the following steps from top to bottom. These steps increase in complexity of the problem and in range of the technical environment.
If one step is not resolving the issue, continue to follow each successive step until your issue is fixed.
1) Refresh your browser window.
2) Close the browser (alt+F4 [win]; cmd+Q [mac]) and re-open it. Visit link again.
3) Try a different browser.
4) Open browser settings and empty cookie and history cache. Close the browser as in step 2) and reopen the browser.
5) If the problem still persists repeat step 4) in emptying the cache. Quit the browser app and reboot your computer.
If all these steps haven't helped and two different browser applications have shown the same results it might be due to a system wide issue.
Try if available a different computer or device of your choice. Make sure you are still connected to the internet and other apps or services which rely on a internet connection are properly working.
Wifi and internet:
1) Try if any other website or app can connect to the internet.
2) If you have other wifi or internet based devices around, try them in order to find out if the wifi issue is local on your malfunctioning device.
If all your devices can't connect to the internet or have no wifi signal, jump ahead to step 6) and reboot your router/switch off for at least 10 seconds.
3) If other devices in your home environment have a wifi connection and work properly but the one you intend to use doesn't, quit or close the browser app, turn wifi off, then on, then reopen the browser.
4) Check wires and cables that go in and out of the router. There might be an intermittent connection causing the problem. Also check the power outlets and internet cable wall plug.
5) Go to system settings and forget your current wifi connection. Reboot the computer and type in your Wifi Name/ ID and Password, if applicable.
Once you are connected to your wifi, try again.
6) Sometimes your wifi doesn't appear in the list after having forgotten it in the settings. This might be due to a router not working properly. Unplug the router for at least 10 seconds or press the reset button with a pen. A short tap will do. The re-boot of the rooter takes often between 1 and 5 minutes. When all the lights for wifi, internet and alike are back on and back to normal, look for your wifi name and enter the password to reconnect. (If not already tested, check all the wires and power chords that go out of and into the router. Also follow those chords to the sockets and see if a cable got loose.)
Alternatives. If you possess a LAN or network cable, circumvent the wireless connection and connect your computer directly with the routers LAN port.
Microphone and camera Probleme:
1) Check your general settings in the computer, to find out what kind of camera and microphone are used.
1a) If you want to use a different mic or camera than the one that is currently operating, connect the new device(s) and select them in settings.
1b) If the devices are displayed and chosen but you still don't get sound or video in/out try:
- disconnecting and reconnecting the device(s)
- make sure you chose the right jack (some computers have individual mic jacks / headphones vice versa)
- reboot your computer or the device your currently using.
If you are using a smart phone or tablet, do a hard reset in order to have it completely reboot.
If you enter the room and your browser is not asking for permission to use your mic and or camera,
logg off and join the session anew.
Firewall: If your are filtering in and outgoing traffic through a firewall, you could try to bypass or wave through connections for the ports UDP-1000 and TCP-443.
Mozilla Firefox seems to be malfunctioning in some versions in combination with Zoom. If you are experiencing problems while using the firefox app, try switching to a different browser like, safari, opera, etc.