Remote Desktop stuck at Loading Virtual Machine

We have a Terminal Services environment with following configuration

Server A - RD Gateway + Connection Broker Server 1 to 20 - RD Session Host

We have 7 collections and session hosts servers are assigned to different collections based on application version we require. All servers are running Windows Server 2016 Standard. We have wildcard certificates installed on Server A for all services.

Our environment does not uses virtual machine based deployment. Never had any. It has been working fine but lately lot of users get stuck at LOADING VIRTUAL MACHINE.

When we check in the event log in the gateway - there is an event 801 like following

RD Connection Broker successfully processed the connection request for user XX. Redirection info: Target Name = XX Target IP Address = 192.168.110.72 Target Netbios = XX Target FQDN = XX Disconnected Session Found = 0x0

After around 1 min there is an event 819 like following:

This connection request has timed out. User could not log on to the end point within the alloted time. Remote Desktop Connection Broker will stop monitoring this connection request.

There is absolutely no event on the session host server. We are able to connect to the session host server directly. We have tried almost everything but could not find a solution.

Some urgent advise will be helpful.

Thanks, RJ

17-04-2022 Upon more investigation, this is not happening on all clients. On the client where this is happening there are errors like following in the local Terminal Services - Client ActiveX Core

Component name:CAAClientAdapter, :: 'm_spHelper->ReadCreds failed' in CAAClientAdapter::CreateTunnel at 380 err=[0xffffffff], Error code:0xFFFFFFFF

Component name:CClientProxyTransport, :: 'm_ClientAdapter->CreateTunnel failed' in CProxyRawTrans::CreateProxyConnection at 2132 err=[0x800759d9], Error code:0x800759D9

Component name:CClientProxyTransport, :: 'Gateway connection time out is 90' in CClientHTTPProxyTransport::Connect at 1098 err=[0x800759d9], Error code:0x800759D9

Component name:CClientProxyTransport, :: 'CreateConnection failed' in CClientHTTPProxyTransport::Connect at 1107 err=[0x800759d9], Error code:0x800759D9