With the extra burden now being placed on various online services, learning platforms, and websites, some will "crash" or become non-accessible on occasion.
Many of these services will know that their systems have gone down and will do their best to get them back to operation as soon as they can.
Please exercise patience when these problems occur by waiting 30 - 60 minutes before trying to access a service or website again.
Trying to access a service or website repeatedly over a short amount of time (i.e. "spamming the refresh button") only adds to the problem - it actually creates a "Denial of Service attack" when enough people do this at the same time.
Thank you for your understanding!