Sometimes the vpn cannot start on iOS，the key logs :
15:24:30.262377+0800 nesessionmanager NESMVPNSession[Primary Tunnel:WeLine SDVN:9A1A565B-4DEA-4ED6-A954-11E04B44CFFC:(null)]: Received a start command from LenovoLink[2472]
15:24:30.262402+0800 nesessionmanager Registering session NESMVPNSession[Primary Tunnel:WeLine SDVN:9A1A565B-4DEA-4ED6-A954-11E04B44CFFC:(null)]
15:24:30.262556+0800 nesessionmanager <NESMServer: 0x143e07e40>: Register Enterprise VPN Session: NESMVPNSession[Primary Tunnel:WeLine SDVN:9A1A565B-4DEA-4ED6-A954-11E04B44CFFC:(null)]
15:24:30.262589+0800 nesessionmanager NESMVPNSession[Primary Tunnel:WeLine SDVN:9A1A565B-4DEA-4ED6-A954-11E04B44CFFC:(null)]: Successfully registered
15:24:30.262638+0800 nesessionmanager NESMVPNSession[Primary Tunnel:WeLine SDVN:9A1A565B-4DEA-4ED6-A954-11E04B44CFFC:(null)] in state NESMVPNSessionStateUpdating: received start message
...
15:24:51.343767+0800 nesessionmanager NESMVPNSession[Primary Tunnel:WeLine SDVN:9A1A565B-4DEA-4ED6-A954-11E04B44CFFC:(null)]: State timer (300 seconds) fired in state NESMVPNSessionStateUpdating
15:24:51.344305+0800 nesessionmanager NESMVPNSession[Primary Tunnel:WeLine SDVN:9A1A565B-4DEA-4ED6-A954-11E04B44CFFC:(null)] in state NESMVPNSessionStateUpdating: timed out
15:24:51.345617+0800 nesessionmanager NESMVPNSession[Primary Tunnel:WeLine SDVN:9A1A565B-4DEA-4ED6-A954-11E04B44CFFC:(null)]: Leaving state NESMVPNSessionStateUpdating
15:24:51.348733+0800 nesessionmanager NESMVPNSession[Primary Tunnel:WeLine SDVN:9A1A565B-4DEA-4ED6-A954-11E04B44CFFC:(null)]: Entering state NESMVPNSessionStateDisposing, timeout 5 seconds
15:24:51.349478+0800 nesessionmanager net.memenet.WeLine[426]: disposing
15:24:51.351587+0800 nesessionmanager NESMVPNSession[Primary Tunnel:WeLine SDVN:9A1A565B-4DEA-4ED6-A954-11E04B44CFFC:(null)]: status changed to disconnecting
15:24:51.357284+0800 nesessionmanager NESMVPNSession[Primary Tunnel:WeLine SDVN:9A1A565B-4DEA-4ED6-A954-11E04B44CFFC:(null)]: Resetting VPN On Demand
15:24:51.358434+0800 nesessionmanager net.memenet.WeLine[426]: Tearing down agent connection
15:24:51.359272+0800 nesessionmanager Found 0 (0 active) registrations for net.memenet.WeLine.provider (com.apple.networkextension.packet-tunnel)
15:24:51.360821+0800 nesessionmanager net.memenet.WeLine[426]: XPC connection went away
15:24:51.362919+0800 nesessionmanager NEVPNTunnelPlugin(net.memenet.WeLine[inactive]): Tearing down plugin connection
15:24:51.408596+0800 nesessionmanager NESMVPNSession[Primary Tunnel:WeLine SDVN:9A1A565B-4DEA-4ED6-A954-11E04B44CFFC:(null)]: Plugin is installed
15:24:51.408807+0800 nesessionmanager NESMVPNSession[Primary Tunnel:WeLine SDVN:9A1A565B-4DEA-4ED6-A954-11E04B44CFFC:(null)] in state NESMVPNSessionStateDisposing: plugin NEVPNTunnelPlugin(net.memenet.WeLine[inactive]) dispose complete
15:24:51.408936+0800 nesessionmanager NESMVPNSession[Primary Tunnel:WeLine SDVN:9A1A565B-4DEA-4ED6-A954-11E04B44CFFC:(null)] in state NESMVPNSessionStateDisposing: all plugins have disposed
15:24:51.409192+0800 nesessionmanager NEVPNTunnelPlugin(net.memenet.WeLine[inactive]): Tearing down plugin connection
15:24:51.409316+0800 nesessionmanager NESMVPNSession[Primary Tunnel:WeLine SDVN:9A1A565B-4DEA-4ED6-A954-11E04B44CFFC:(null)]: Leaving state NESMVPNSessionStateDisposing
15:24:51.409441+0800 nesessionmanager NESMVPNSession[Primary Tunnel:WeLine SDVN:9A1A565B-4DEA-4ED6-A954-11E04B44CFFC:(null)]: Entering state NESMVPNSessionStateIdle
15:24:51.409750+0800 nesessionmanager NESMVPNSession[Primary Tunnel:WeLine SDVN:9A1A565B-4DEA-4ED6-A954-11E04B44CFFC:(null)]: status changed to disconnected, last stop reason Stop command received
it seems the packet tunnel provider is not started because of a XPC error?