This error is a bit misleading. While this error is true, it is frequently not related to a firewall configuration for port 443. Instead this issue often indicates that the device is not able to connect to the NTP servers (see the network requirements) to set the clock. In this case, the device cannot establish any HTTPS traffic.
This error can occur because the Raspberry Pi does not have any built-in Real Time Clock (RTC). This means that when you turn on the Raspberry Pi, the device does not know what time it is without connecting to the NTP servers.