Does it work if you switch your project to use a secure https connection?

Yes, I'm already using a https connection (using a self-signed certificate) in its bindings.

This seems to be related to your app not using a secure base address. When I adjust your Startup.cs file and hard code your base address (line 48), it works.

string baseAddress = "https://localhost:44328/"; // addressFeature.Addresses.First();

 Did you try hosting the pre-rendered solution in your local or remote IIS?

When I try to hard code the URL of the server in IIS (https://testserver.com/) the get the following error. I'm trying to make my invalid certificate valid to get rid of this exception.

An unhandled exception occurred while processing the request.

RpcException: Status(StatusCode="Internal", Detail="Error starting gRPC call. HttpRequestException: The SSL connection could not be established, see inner exception. AuthenticationException: The remote certificate is invalid according to the validation procedure: RemoteCertificateNameMismatch", DebugException="System.Net.Http.HttpRequestException: The SSL connection could not be established, see inner exception.
---> System.Security.Authentication.AuthenticationException: The remote certificate is invalid according to the validation procedure: RemoteCertificateNameMismatch
at System.Net.Security.SslStream.SendAuthResetSignal(ProtocolToken message, ExceptionDispatchInfo exception) in System.Net.Security.dll:token 0x60002e7+0x35
at System.Net.Security.SslStream.ForceAuthenticationAsync[TIOAdapter](TIOAdapter adapter, Boolean receiveFirst, Byte[] reAuthenticationData, Boolean isApm) in System.Net.Security.dll:token 0x60002e4+0x608
at System.Net.Http.ConnectHelper.EstablishSslConnectionAsyncCore(Boolean async, Stream stream, SslClientAuthenticationOptions sslOptions, CancellationToken cancellationToken) in System.Net.Http.dll:token 0x600056c+0x95
--- End of inner exception stack trace ---

I was running on local IIS. I noticed in your screenshot at the GitHub link in your original post that your security certificate wasn't setup properly, since your browser was displaying the "Not Secure" notice. I suspect the hard-coded approach will work once you have your certificate setup properly.

can you please help me understand why the project with pre-rendering needs to have an authorized certificate to run in the IIS whereas the same project that is not pre-rendering does not need it?

unfortunately, I cannot add a trusted certificate to my local machine. So I added a trusted certificate provided by my organization in the remote server IIS, and I still get the initial exception. If I hard code the base URL address then the error says: Error starting gRPC call. HttpRequestException: No connection could be made because the target machine actively refused it.

Can you please provide a repo of the code that you are pre-rendering and able to host it in the IIS server using Grpc call?

I used your repo HERE.

I adjusted your ConfigureServices method of your Startup.cs file to this to get it working without hard-coding the Uri:

public void ConfigureServices(IServiceCollection services)
{
    services.AddControllersWithViews();
    services.AddRazorPages();
     ervices.AddGrpc();
    services.AddScoped<HttpClient>(sp =>
    {
         // Get the address that the app is currently running at
        var uriHelper = sp.GetRequiredService<NavigationManager>();
        string baseAddress = uriHelper.BaseUri;
        return new HttpClient { BaseAddress = new Uri(baseAddress) };
    });

    services.AddScoped(services =>
    {
        var uriHelper = services.GetRequiredService<NavigationManager>();
        string baseAddress = uriHelper.BaseUri;
        var httpHandler = new GrpcWebHandler(GrpcWebMode.GrpcWeb, new HttpClientHandler());
        return GrpcChannel.ForAddress(baseAddress, new GrpcChannelOptions { HttpHandler = httpHandler });
    });
}

This did require adding a using directive for Microsoft.AspNetCore.Components

As far as why it requires a secure connection when prerendered and not when rendered in the Client, I'm not sure. This is the first time I've ever messed with gRPC. I would guess it has something to do with prerendering occurring on the Server compared to it running in the JavaScript sandbox of the browser otherwise.

Now when I try this snippet of code and host this simple pre-rendered project in my remote IIS, there is a different error.

RpcException: Status(StatusCode="PermissionDenied", Detail="Bad gRPC response. HTTP status code: 403")

Same project when hosted in local IIS:

An unhandled exception occurred while processing the request.

RpcException: Status(StatusCode="Internal", Detail="Error starting gRPC call. HttpRequestException: The SSL connection could not be established, see inner exception. AuthenticationException: The remote certificate is invalid according to the validation procedure: RemoteCertificateNameMismatch", DebugException="System.Net.Http.HttpRequestException: The SSL connection could not be established, see inner exception.
---> System.Security.Authentication.AuthenticationException: The remote certificate is invalid according to the validation procedure: RemoteCertificateNameMismatch
at System.Net.Security.SslStream.SendAuthResetSignal(ProtocolToken message, ExceptionDispatchInfo exception) in System.Net.Security.dll:token 0x60002e7+0x35
at System.Net.Security.SslStream.ForceAuthenticationAsync[TIOAdapter](TIOAdapter adapter, Boolean receiveFirst, Byte[] reAuthenticationData, Boolean isApm) in System.Net.Security.dll:token 0x60002e4+0x608
at System.Net.Http.ConnectHelper.EstablishSslConnectionAsyncCore(Boolean async, Stream stream, SslClientAuthenticationOptions sslOptions, CancellationToken cancellationToken) in System.Net.Http.dll:token 0x600056c+0x95
--- End of inner exception stack trace ---

Looks like no one has yet encountered this kind of error and not sure of any resolution steps further

I believe your best next step would be to seek out help setting up your local development environment. Mostly, it sounds like you're going to need to get a security certificate installed correctly locally. Until you rule things out related to your development environment, you're going to have too many potential causes for your errors.