Keep getting failed to get device list -999

The cams working well for years but recently I keep getting failed to get device list -999

I searched web it’s cache issue, but I’ve removed and reinstalled app multiple times on both iphone and ipad. No luck, why?

Are you continuing to get the error message, or does it show up momentarily and then clear (and work normally)?

It’s suddenly start to have this issue and never able to see any cam ever.

I have been receiving “Failed to update device list (error code -999)” for the past couple weeks. Does anybody know the cause or have a solution to this issue? Latest version of the iOS app.