Just as I thought. I found the answer. Turning Windows Firewall off helped. However I'd love to know which ports XPUIPC uses.

Hi!

First off all thanks for this great program!
Recently I switched to X-plane 10 64-bit. I run Plan-G on another computer (lets call it 192.168.0.100). X-Plane runs on 192.168.0.105. Those IPs don't change. I installed XPUIPC 2.0.0 in X-plane PC and XPWideClient on remote. I think that manual was written for an older version of XPUIPC btw. I entered 192.168.0.105 in xpuipc ini file and both IPs in XPWideClient ini. XPWideClients says it receives UDP packets from 192.168.0.105 so it should work fine. However when I try to connect in Plan-G almost nothing happens.

Here are logs of Plan-G
11:00:12.0 Initiating FSUIPC/XPUIPC connection.
11:00:12.0 FSUIPC/XPUIPC.Connect
11:00:12.6 Connect: FSUIPC.FSUIPCException: FSUIPC Error #14: FSUIPC_ERR_RUNNING. FSUIPC is not running.
   at FSUIPC.FSUIPCConnection.Open(Byte ClassInstance, FlightSim RequiredFlightSimVersion)
   at Plan_G3.Model.MyFSUIPC.Connect()
11:00:12.6 SetFSConnected: System.NullReferenceException: Object reference not set to an instance of an object.
   at Plan_G3.Model.MyFSUIPC.Disconnect()
   at Plan_G3.Model.MyFSUIPC.Connect()
   at Plan_G3.ViewModel.MainViewModel.SetFSConnected(Boolean value)
11:00:16.2 SetFSConnected: System.NullReferenceException: Object reference not set to an instance of an object.
   at Plan_G3.Model.MyFSUIPC.Disconnect()
   at Plan_G3.ViewModel.MainViewModel.SetFSConnected(Boolean value)
11:00:18.2 Cleanup

I've read the manual.