我尝试在MAC上安装Visual Studio 2017。 安装过程中出错（Mac iOS有High Sierra，版本10.13.2）..任何帮助将不胜感激。 Mac PC是新的，安装了Xcode版本9.2。
Error downloading from Mono server. Mono Framework.
Message: The operation has timed out.
Exception type: System.Net.WebException
at System.Net.WebConnectionStream.Read (System.Byte[] buffer, System.Int32 offset, System.Int32 size) [0x00055] in /Library/Frameworks/Xamarin.Mac.framework/Versions/2.10.0.113/src/mono/mcs/class/System/System.Net/WebConnectionStream.cs:338
at Xamarin.Web.Installer.DownloadService.DoDownload (System.Int64 totalBytes, System.IO.Stream responseStream, System.IO.Stream outputStream, System.Object state) [0x00087] in /Users/builder/data/lanes/5758/ce9029ec/source/installer/Xamarin.Web.Installer/DownloadService.cs:285
at Xamarin.Web.Installer.Utilities.DownloadUrl (System.Net.WebResponse response, System.String url, System.Action`4[T1,T2,T3,T4] doDownload, System.Action`1[T] reportProgress, System.Boolean noCache, System.Object state, System.IO.Stream outputStream, System.String targetFileName) [0x000c7] in /Users/builder/data/lanes/5758/ce9029ec/source/installer/Xamarin.Web.Installer/Utilities.cs:1071
Mono Framework installation failed with more than one exception (Attempt #3)
Message: Some installation errors are present.
Exception type: System.AggregateException
at Xamarin.Web.Installer.Installer.BaseSoftwareItem.ValidateDownloadItem () [0x0008f] in /Users/builder/data/lanes/5758/ce9029ec/source/installer/Xamarin.Web.Installer/Installer/BaseSoftwareItem.cs:501
at Xamarin.Web.Installer.Installer.BaseSoftwareItem.Install (System.UInt32 tryNumber) [0x0003e] in /Users/builder/data/lanes/5758/ce9029ec/source/installer/Xamarin.Web.Installer/Installer/BaseSoftwareItem.cs:289
at MacInstaller.WizardPageInstallationController.InstallationWorker () [0x00145] in /Users/builder/data/lanes/5758/ce9029ec/source/installer/MacInstaller.Universal/WizardPageInstallationController.cs:541
at System.Net.WebConnectionStream.Read (System.Byte[] buffer, System.Int32 offset, System.Int32 size) [0x00055] in /Library/Frameworks/Xamarin.Mac.framework/Versions/2.10.0.113/src/mono/mcs/class/System/System.Net/WebConnectionStream.cs:338
at Xamarin.Web.Installer.DownloadService.DoDownload (System.Int64 totalBytes, System.IO.Stream responseStream, System.IO.Stream outputStream, System.Object state) [0x00087] in /Users/builder/data/lanes/5758/ce9029ec/source/installer/Xamarin.Web.Installer/DownloadService.cs:285
at Xamarin.Web.Installer.Utilities.DownloadUrl (System.Net.WebResponse response, System.String url, System.Action`4[T1,T2,T3,T4] doDownload, System.Action`1[T] reportProgress, System.Boolean noCache, System.Object state, System.IO.Stream outputStream, System.String targetFileName) [0x000c7] in /Users/builder/data/lanes/5758/ce9029ec/source/installer/Xamarin.Web.Installer/Utilities.cs:1071
at Xamarin.Web.Installer.Installer.BaseSoftwareItem.ValidateDownloadItem () [0x0008f] in /Users/builder/data/lanes/5758/ce9029ec/source/installer/Xamarin.Web.Installer/Installer/BaseSoftwareItem.cs:501
at Xamarin.Web.Installer.Installer.BaseSoftwareItem.Install (System.UInt32 tryNumber) [0x0003e] in /Users/builder/data/lanes/5758/ce9029ec/source/installer/Xamarin.Web.Installer/Installer/BaseSoftwareItem.cs:289
at MacInstaller.WizardPageInstallationController.InstallationWorker () [0x00145] in /Users/builder/data/lanes/5758/ce9029ec/source/installer/MacInstaller.Universal/WizardPageInstallationController.cs:541
at System.Net.WebConnectionStream.Read (System.Byte[] buffer, System.Int32 offset, System.Int32 size) [0x00055] in /Library/Frameworks/Xamarin.Mac.framework/Versions/2.10.0.113/src/mono/mcs/class/System/System.Net/WebConnectionStream.cs:338
at Xamarin.Web.Installer.DownloadService.DoDownload (System.Int64 totalBytes, System.IO.Stream responseStream, System.IO.Stream outputStream, System.Object state) [0x00087] in /Users/builder/data/lanes/5758/ce9029ec/source/installer/Xamarin.Web.Installer/DownloadService.cs:285
at Xamarin.Web.Installer.Utilities.DownloadUrl (System.Net.WebResponse response, System.String url, System.Action`4[T1,T2,T3,T4] doDownload, System.Action`1[T] reportProgress, System.Boolean noCache, System.Object state, System.IO.Stream outputStream, System.String targetFileName) [0x000c7] in /Users/builder/data/lanes/5758/ce9029ec/source/installer/Xamarin.Web.Installer/Utilities.cs:1071
at Xamarin.Web.Installer.Installer.BaseSoftwareItem.ValidateDownloadItem () [0x0008f] in /Users/builder/data/lanes/5758/ce9029ec/source/installer/Xamarin.Web.Installer/Installer/BaseSoftwareItem.cs:501
at Xamarin.Web.Installer.Installer.BaseSoftwareItem.Install (System.UInt32 tryNumber) [0x0003e] in /Users/builder/data/lanes/5758/ce9029ec/source/installer/Xamarin.Web.Installer/Installer/BaseSoftwareItem.cs:289
at MacInstaller.WizardPageInstallationController.InstallationWorker () [0x00145] in /Users/builder/data/lanes/5758/ce9029ec/source/installer/MacInstaller.Universal/WizardPageInstallationController.cs:541
at System.Net.WebConnectionStream.Read (System.Byte[] buffer, System.Int32 offset, System.Int32 size) [0x00055] in /Library/Frameworks/Xamarin.Mac.framework/Versions/2.10.0.113/src/mono/mcs/class/System/System.Net/WebConnectionStream.cs:338
at Xamarin.Web.Installer.DownloadService.DoDownload (System.Int64 totalBytes, System.IO.Stream responseStream, System.IO.Stream outputStream, System.Object state) [0x00087] in /Users/builder/data/lanes/5758/ce9029ec/source/installer/Xamarin.Web.Installer/DownloadService.cs:285
at Xamarin.Web.Installer.Utilities.DownloadUrl (System.Net.WebResponse response, System.String url, System.Action`4[T1,T2,T3,T4] doDownload, System.Action`1[T] reportProgress, System.Boolean noCache, System.Object state, System.IO.Stream outputStream, System.String targetFileName) [0x000c7] in /Users/builder/data/lanes/5758/ce9029ec/source/installer/Xamarin.Web.Installer/Utilities.cs:1071