What kind of a device? It makes a difference since with Core and Photon, connected generally means “has an open TCP stream from device to cloud” but with Electron, there is no such thing.
Linking to a post where this is documented in more detail. This remains a significant problem for us, and appears to have gotten worse with 4.9. In the short term I’m writing a server executed job to reset Photons that are in this state.
I replied in the other thread, but I’ll reply here as well. I wasn’t aware this was an ongoing issue, I’ll look into this. If you could send me firmware or details on reproducing this issue (listing all devices vs. get device attributes, etc), that would help.