Vpilot can't connect to network after a prompt window pop up

P3D V5.4 Aerosoft 330…Vpilot ver.3.5.2
Have been online since cockpit preparation, during hours flight everything looks fine. But it suddenly poped up a window says simulator seems frozen (details I can’t remember)…then disconnect.
I immediately check P3D, it still works. Then I try launch Vpilot again, but I can’t see simulator version info in Messages window, I know it’s different like usual.
But I still click Connect button, and continue clicking connect on the next window, then a “command failed” alert comes out – Please ensure that a flight is loaded.
I’m quite sure I’m in flight now, so any suggestion? :sob: