I have an ATA Server and two DCs on-premises running the Lightweight Gateway. This configuration has been in place without any issues for over a year. We setup a third DC in Azure. The Azure subnet is connected with a VPN to to our on-premises network with no connectivity issues in regards to other servers in the two sites. The third DC has the Lightweight Gateway installed but will not start the service. We are able to connect to the ATA web site from the Azure DC. I also migrated the ATA server from our on-prem network to Azure and the on-prem DCs communicate fine to the ATA server but still cannot get the Azure DC working.
This error is present in the Microsoft.Tri.Gateway-Errors log and is generated every time the service attempts to start;
2018-11-13 14:09:14.0579 6632 5 Error [Enumerable] System.InvalidOperationException: Sequence contains more than one element
at System.Linq.Enumerable.Single[TSource](IEnumerable`1 source)
at async Microsoft.Tri.Gateway.Resolution.DirectoryServices.DirectoryServicesClient.ConnectDisconnectedDomainControllersAsync(?)
at async Microsoft.Tri.Gateway.Resolution.DirectoryServices.DirectoryServicesClient.OnInitializeAsync(?)
at async Microsoft.Tri.Infrastructure.Framework.Module.InitializeAsync(?)
at async Microsoft.Tri.Infrastructure.Framework.ModuleManager.OnInitializeAsync(?)
at async Microsoft.Tri.Infrastructure.Framework.Module.InitializeAsync(?)
at async Microsoft.Tri.Infrastructure.Framework.Service.OnStartAsync(?)
at Microsoft.Tri.Infrastructure.Framework.Service.OnStart(String[] args)
