From my experience as a web developer, sites go down when they’re overloaded with requests (run out of memory), or when they’re down for maintenance/upgrades, or when there’s an issue with a data center ( see Server Status: Updates - #3 by Pavel).
It’s annoying, and I’m sure the team are investigating. @Stefan it think it would instill confidence for CoSpaces Edu educators if a server status page could be developed to proactively show where in the world issues are occurring which the team are aware of.