Check the status and availability of Vivaldi's online services on vivaldistatus.com.
Tag: sync
Tip #149
Download the backup encryption key to be able to restore access to synced data even when you have forgotten the encryption password.
Tip #97
Find debug-level information and controls about the state of Sync on vivaldi://sync.
Tip #78
Synchronize your browser data to access open tabs on other devices.
Tip #23
Use Sync to access tabs that are open in Vivaldi on your other devices.