Error when using online data source offline mode

I'm connecting to a VPN solution, then opening an online data source (RDMO). Since I have no connection to that data source, I am eventually prompted for offline mode, which I click "yes". However, after connecting to a resource, I keep getting the following every couple of minutes:

Enterprise Edition 6.0.0.0
WebException - Unable to connect to the remote server
at System.Net.HttpWebRequest.GetRequestStream(TransportContext& context)
at System.Net.HttpWebRequest.GetRequestStream()
at System.Web.Services.Protocols.SoapHttpClientProtocol.Invoke(String methodName, Object[] parameters)
at Devolutions.RemoteDesktopManager.RDMOProxy.RDMServices.KeepAlive()
at Devolutions.RemoteDesktopManager.Business.DataSources.RDMOConnectionDataSource.timerKeepAlive_Tick(Object sender, EventArgs e)
at System.Windows.Forms.Timer.OnTick(EventArgs e)
at System.Windows.Forms.Timer.TimerNativeWindow.WndProc(Message& m)
at System.Windows.Forms.NativeWindow.Callback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)
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SocketException - A connection attempt failed because the connected party did not properly respond after a period of time, or established connection failed because connected host has failed to respond <removed IP>:443
at System.Net.Sockets.Socket.DoConnect(EndPoint endPointSnapshot, SocketAddress socketAddress)
at System.Net.Sockets.Socket.InternalConnect(EndPoint remoteEP)
at System.Net.ServicePoint.ConnectSocketInternal(Boolean connectFailure, Socket s4, Socket s6, Socket& socket, IPAddress& address, ConnectSocketState state, IAsyncResult asyncResult, Int32 timeout, Exception& exception)

That one is REALLY annoying, as it usually stops responding for a while before showing this. Also, after disconnecting from the VPN network, and trying to go online in RDM, I get

Enterprise Edition 6.0.0.0
NullReferenceException - Object reference not set to an instance of an object.
at Devolutions.RemoteDesktopManager.Frames.ConnectionViews.FreConnectionTreeView.get_CurrentGroupConnection()
at Devolutions.RemoteDesktopManager.Forms.FrmMainBase.get_CurrentGroupConnection()
at Devolutions.RemoteDesktopManager.Forms.FrmMainDockable.LoadConnectionDetailsInControl(Connection connection)
at Devolutions.RemoteDesktopManager.Forms.FrmMainDockable.cbDataSources_SelectedIndexChanged(Object sender, EventArgs e)
at System.Windows.Forms.ComboBox.OnSelectedIndexChanged(EventArgs e)
at System.Windows.Forms.ComboBox.set_SelectedIndex(Int32 value)
at Devolutions.RemoteDesktopManager.Forms.FrmMainBase.RefreshDataSources()
at Devolutions.RemoteDesktopManager.Managers.OfflineManager.GoOnline()
at Devolutions.RemoteDesktopManager.Managers.MainMenuManager.mnuGoOnline_Click(Object sender, EventArgs e)
at System.Windows.Forms.ToolStripItem.RaiseEvent(Object key, EventArgs e)
at System.Windows.Forms.ToolStripMenuItem.OnClick(EventArgs e)
at System.Windows.Forms.ToolStripItem.HandleClick(EventArgs e)
at System.Windows.Forms.ToolStripItem.HandleMouseUp(MouseEventArgs e)
at System.Windows.Forms.ToolStripItem.FireEventInteractive(EventArgs e, ToolStripItemEventType met)
at System.Windows.Forms.ToolStripItem.FireEvent(EventArgs e, ToolStripItemEventType met)
at System.Windows.Forms.ToolStrip.OnMouseUp(MouseEventArgs mea)
at System.Windows.Forms.ToolStripDropDown.OnMouseUp(MouseEventArgs mea)
at System.Windows.Forms.Control.WmMouseUp(Message& m, MouseButtons button, Int32 clicks)
at System.Windows.Forms.Control.WndProc(Message& m)
at System.Windows.Forms.ScrollableControl.WndProc(Message& m)
at System.Windows.Forms.ToolStrip.WndProc(Message& m)
at System.Windows.Forms.ToolStripDropDown.WndProc(Message& m)
at System.Windows.Forms.Control.ControlNativeWindow.OnMessage(Message& m)
at System.Windows.Forms.Control.ControlNativeWindow.WndProc(Message& m)
at System.Windows.Forms.NativeWindow.Callback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)