BlazorServer Web App falls flat when 20 odd users connect to the site?

As mentioned in the subject line our Blazor Server web app falls flat when 20 odd users connect to the site at once!

Below are the details of the VM running the web app, as well as a bit more details on the web app.

Windows edition

Windows Server 2019 Datacenter

SystemProcessor: Intel(R) Xeon(R) Platinum 8272CL CPU @ 2.60GHz 2.59GHzInstalled memory (RAM): 8.00GBSystem type: 64-bit Operating System, x64-based processor

Here's more detail about the hosting environment for the Blazor Server web app

Internet Information Services (IIS) Manager

Microsoft Windows ServerVersion 1809 (OS Build 17763.7314)

Internet Information Services (Version 10.0.17763.1)

We've tried quite a number of fixes, with the most recent being the following suggestions I received from CoPilot.

• In your IIS site’s web.config, increase WebSocket and request limits:

  <system.webServer><webSocket enabled="true" /><security><requestFiltering><requestLimits maxAllowedContentLength="2147483648" /></requestFiltering></security></system.webServer>

• In Startup.cs or Program.cs, configure SignalR keep-alive:

  builder.Services.AddServerSideBlazor()                .AddHubOptions(options =>                {                    options.ClientTimeoutInterval = TimeSpan.FromSeconds(60);                    options.KeepAliveInterval = TimeSpan.FromSeconds(15);                });

Serilog file info:

Microsoft.JSInterop.JSDisconnectedException: JavaScript interop calls cannot be issued at this time. This is because the circuit has disconnected and is being disposed.   at Microsoft.AspNetCore.Components.Server.Circuits.RemoteJSRuntime.BeginInvokeJS(Int64 asyncHandle, String identifier, String argsJson, JSCallResultType resultType, Int64 targetInstanceId)   at Microsoft.JSInterop.JSRuntime.InvokeAsync[TValue](Int64 targetInstanceId, String identifier, CancellationToken cancellationToken, Object[] args)   at Microsoft.JSInterop.JSRuntime.InvokeAsync[TValue](Int64 targetInstanceId, String identifier, Object[] args)   at Microsoft.JSInterop.JSRuntimeExtensions.InvokeVoidAsync(IJSRuntime jsRuntime, String identifier, Object[] args)   at Radzen.Blazor.RadzenContextMenu.Close()   at Radzen.Blazor.RadzenContextMenu.DisposeAsync()   at Microsoft.AspNetCore.Components.RenderTree.Renderer.<>c__DisplayClass85_0.<<Dispose>g__HandleAsyncExceptions|1>d.MoveNext()2025-06-27 11:20:45 [Warning]  Unhandled exception rendering component: "JavaScript interop calls cannot be issued at this time. This is because the circuit has disconnected and is being disposed."Microsoft.JSInterop.JSDisconnectedException: JavaScript interop calls cannot be issued at this time. This is because the circuit has disconnected and is being disposed.   at Microsoft.AspNetCore.Components.Server.Circuits.RemoteJSRuntime.BeginInvokeJS(Int64 asyncHandle, String identifier, String argsJson, JSCallResultType resultType, Int64 targetInstanceId)   at Microsoft.JSInterop.JSRuntime.InvokeAsync[TValue](Int64 targetInstanceId, String identifier, CancellationToken cancellationToken, Object[] args)   at Microsoft.JSInterop.JSRuntime.InvokeAsync[TValue](Int64 targetInstanceId, String identifier, Object[] args)   at Microsoft.JSInterop.JSRuntimeExtensions.InvokeVoidAsync(IJSRuntime jsRuntime, String identifier, Object[] args)   at Radzen.Blazor.RadzenContextMenu.Close()   at Radzen.Blazor.RadzenContextMenu.DisposeAsync()   at Microsoft.AspNetCore.Components.RenderTree.Renderer.<>c__DisplayClass85_0.<<Dispose>g__HandleAsyncExceptions|1>d.MoveNext()2025-06-27 11:20:45 [Error]  Unhandled exception in circuit '"Owrj5xkrshch_9awHfgx7LN_5mSfXDitIUIJHf_MU9o"'.

To be honest I'm a bit stumped as to why it's still giving issues when multiple users connect, so any real help would really be appreciated.

Thanks very much.