Other POS coins are issuing similar advice. I wonder whether Internet Service Providers are now clamping down more on extended download use, such as wallet syncing, by switching the service off every now and then. I have mentioned this possibility before. I've been recently experiencing intermittent service problems with TalkTalk.
Zeit Syncing Tips for PoS
Keep your Wallet Locked when you are not Synced with the network if you have coins in your wallet.
The Green Check mark will appear a few minutes before synced , but may not be completely synced yet,
Move the mouse over the Green Check mark , and it will show
Last Received Block was Generated (Time) ago.
When it says 1 minute or less , then it is a good time to unlock the wallet and let it stake.
If it says 5 minutes and you check it again a few minutes later and says 15 minutes, then close and restart your wallet, and it will sync quickly.
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FYI:
If your ISP has issues, it can cause you to fall out of sync with the current block # and a restart of the wallet may be required.
Great advice. Don't just go by the jolly green tick (some call it a check mark). It will still show a glowing green if your Internet service has been interrupted and you could be well-behind.
Always check that your wallet is actually up-to-date before opening your wallet for staking by hovering your mouse over the green tick.