Dear @thermobee,

Just updated my OC200 to the latest firmware and it didn't come back up after the restart. Omada Cloud also shows it as offline. 

I was literally just troubleshooting it for 1 hour, because it dissappeared this morning. Why did I update it? 

Any ideas? Is there something wrong with the newest firmware?

What's the previous firmware version of your OC200? What's the LED status on the OC200 now?

Please note that the OC200 will be reset when you upgrade the OC200 from Omada Controller version 3.x to the latest SDN Controller version 4.x, which is also noted in the firmware release note. https://www.tp-link.com/support/download/oc200/#Firmware

If you have a backup file of the OC200, please refer to the Omada Controller Upgrade Guide to restore the settings.

Otherwise, you may need to reconfigure the OC200.