I keep getting errors that traffic is too high and I can't access the site. It can be when I am trying to see work, or even logging in for the first time in the morning. Bandwidth issues on the web servers?
Upwork is currently up and running, and there shouldn't be an issue that will prevent you from accessing the site. You can check the status here. Could you please try restarting your modem/router, contacting your Internet Service Provider, or rebooting your computer?