Here is the App Log from my working PC at home connecting to my working setup showing the good thing that happens when you click an app. We get the handshake whereas scroll down to see the bad one and see if it makes sense please?
2022-09-06T15:49:36.918Z GatewayTransport(NORM): GatewayTransport connecting...
2022-09-06T15:49:36.921Z [Connection] Connection state changed to: Opening remote port
2022-09-06T15:49:36.922Z [SessionViewModel] Session 9337799d-dd9f-4958-9827-1f487f9473c9 changed canvas display to none
2022-09-06T15:49:37.404Z GatewayHandshakeState(NORM): Entering Gateway connection state GatewayHandshakeState
2022-09-06T15:49:37.463Z ExtendedAuthenticationState(NORM): Entering Gateway connection state ExtendedAuthenticationState
2022-09-06T15:49:37.463Z ExtendedAuthenticationState(NORM): Prompting for Gateway credentials.
2022-09-06T15:49:37.465Z [Connection] Auth challenge
2022-09-06T15:49:37.465Z [SessionViewModel] Credentials requested (username/password)
2022-09-06T15:49:37.466Z ExtendedAuthenticationState::PromptForCredentials(NORM): Credential aquisition completed. Duration in ms: 2
2022-09-06T15:49:37.586Z TunnelInitiationState(NORM): Entering Gateway connection state TunnelInitiationState
2022-09-06T15:49:37.632Z TunnelAuthorizationState(NORM): Entering Gateway connection state TunnelAuthorizationState
2022-09-06T15:49:37.733Z ChannelInitiationState(NORM): Entering Gateway connection state ChannelInitiationState
2022-09-06T15:49:37.804Z GatewayConnectedState(NORM): Entering Gateway connection state GatewayConnectedState
2022-09-06T15:49:37.804Z Connection(NORM): The transport has connected
2022-09-06T15:49:37.804Z SessionSelectionState(NORM): Entering RDP state SessionSelection
2022-09-06T15:49:37.805Z ConnectionInitiationState(NORM): Entering RDP state ConnectionInitiation
2022-09-06T15:49:37.806Z [Connection] Connection state changed to: Configuring remote connection
2022-09-06T15:49:37.805Z ConnectionInitiationState(NORM): Supported protocols: 7
2022-09-06T15:49:37.806Z ConnectionInitiationState(NORM): There is not sufficient authentication information to use the RDSTLS protocol. Disabling...
2022-09-06T15:49:37.852Z ConnectionInitiationState(NORM): Security protocol 2 was negotiated
2022-09-06T15:49:37.852Z ConnectionInitiationState(NORM): Moving to TlsHandshakeState state
2022-09-06T15:49:37.854Z TlsHandshakeState(NORM): Entering RDP state TlsHandshake
2022-09-06T15:49:37.855Z [Connection] Connection state changed to: Establishing secure connection
2022-09-06T15:49:37.857Z TLS::EnsureOSSLSeeded(NORM): A seed of 256 bytes has been provided for OSSL
2022-09-06T15:49:37.858Z OSSLTransport(NORM): Initiating the TLS handshake.
2022-09-06T15:49:38.005Z OSSLTransport(NORM): Validating the server certificate using an expected certificate...
2022-09-06T15:49:38.005Z OSSLTransport(NORM): Certificate validation complete.
2022-09-06T15:49:38.005Z OSSLTransport(NORM): TLS handshake complete
Now here is the one that fails
022-09-06T15:33:32.276Z [Connection] Connection state changed to: Opening remote port
2022-09-06T15:33:32.276Z [SessionViewModel] Session d9152295-31a8-4984-affd-2079725d252c changed canvas display to none
2022-09-06T15:33:38.813Z [Connection] Disconnect Called
2022-09-06T15:33:38.822Z [Connection] Disconnecting
2022-09-06T15:33:38.829Z WebSocketTransport(ERR): WebSocket error received for url=wss://rdsgw.remotedomain.com:443/remoteDesktopGateway?CorId=%7Bf7246328-ddb2-4b17-aff2-050bd5f90000%7D&ConId=%7B1121a2c2-0037-4249-ba7a-b309779c226a%7D&ClGen=HTML%3D1&ClBld=Type%3DRdClient%3B%20Build%3Dprivate&AuthS=SSPI_NTLM
websockettransport.cpp(304): OnErrorFromJS()
at Logger.a.errorWithoutTimestamp (https://rdsgw.remotedomain.com/rdweb/webclient/js/client.022fca6d.js:1:2890),at Function.<anonymous> (https://rdsgw.remotedomain.com/rdweb/webclient/js/client.022fca6d.js:9:6642),at methodCaller_emscripten$$val_$emscripten$$val_emscripten$$val$ (eval at new_ (https://rdsgw.remotedomain.com/rdweb/webclient/librdp/html/librdphtml.c4af5b60.js:86:202948), <anonymous>:6:26),at __emval_call_method (https://rdsgw.remotedomain.com/rdweb/webclient/librdp/html/librdphtml.c4af5b60.js:86:224640),at invoke_diiiii (https://rdsgw.remotedomain.com/rdweb/webclient/librdp/html/librdphtml.c4af5b60.js:86:256314),at https://rdsgw.remotedomain.com/rdweb/webclient/librdp/html/librdphtml.4fe32847.wasm:wasm-function\[8104\]:0x444f24,at invoke_viii (https://rdsgw.remotedomain.com/rdweb/webclient/librdp/html/librdphtml.c4af5b60.js:86:253457),at https://rdsgw.remotedomain.com/rdweb/webclient/librdp/html/librdphtml.4fe32847.wasm:wasm-function\[1465\]:0xdee11,at https://rdsgw.remotedomain.com/rdweb/webclient/librdp/html/librdphtml.4fe32847.wasm:wasm-function\[1808\]:0x10fbad,at invoke_vii (https://rdsgw.remotedomain.com/rdweb/webclient/librdp/html/librdphtml.c4af5b60.js:86:253620),at https://rdsgw.remotedomain.com/rdweb/webclient/librdp/html/librdphtml.4fe32847.wasm:wasm-function\[7510\]:0x389a61,at invoke_vii (https://rdsgw.remotedomain.com/rdweb/webclient/librdp/html/librdphtml.c4af5b60.js:86:253620),at https://rdsgw.remotedomain.com/rdweb/webclient/librdp/html/librdphtml.4fe32847.wasm:wasm-function\[729\]:0x664a0,at OnMessageCallback.OnMessageCallback$Invoke [as Invoke] (eval at new_ (https://rdsgw.remotedomain.com/rdweb/webclient/librdp/html/librdphtml.c4af5b60.js:86:202948), <anonymous>:9:1),at Worker.<anonymous> (https://rdsgw.remotedomain.com/rdweb/webclient/librdp/html/librdphtml.c4af5b60.js:86:26127)
2022-09-06T15:33:38.830Z WebSocketTransport(NORM): WebSocket closed, url=wss://rdsgw.remotedomain.com:443/remoteDesktopGateway?CorId=%7Bf7246328-ddb2-4b17-aff2-050bd5f90000%7D&ConId=%7B1121a2c2-0037-4249-ba7a-b309779c226a%7D&ClGen=HTML%3D1&ClBld=Type%3DRdClient%3B%20Build%3Dprivate&AuthS=SSPI_NTLM, wasClean=false, code=1006, reason=""
2022-09-06T15:33:38.834Z Connection(ERR): The connection generated an internal exception with disconnect code=ConnectionBroken(8), extended code=<null>, reason=WebSocket closed with code: 1006 reason:
Thrown in thread 1122780 at:
websockettransport.cpp(335)
Call Stack:
Callstacks are currently disabled
connection.cpp(1731): OnException()
at Logger.a.errorWithoutTimestamp (https://rdsgw.remotedomain.com/rdweb/webclient/js/client.022fca6d.js:1:2890),at Function.<anonymous> (https://rdsgw.remotedomain.com/rdweb/webclient/js/client.022fca6d.js:9:6642),at methodCaller_emscripten$$val_$emscripten$$val_emscripten$$val$ (eval at new_ (https://rdsgw.remotedomain.com/rdweb/webclient/librdp/html/librdphtml.c4af5b60.js:86:202948), <anonymous>:6:26),at __emval_call_method (https://rdsgw.remotedomain.com/rdweb/webclient/librdp/html/librdphtml.c4af5b60.js:86:224640),at invoke_diiiii (https://rdsgw.remotedomain.com/rdweb/webclient/librdp/html/librdphtml.c4af5b60.js:86:256314),at https://rdsgw.remotedomain.com/rdweb/webclient/librdp/html/librdphtml.4fe32847.wasm:wasm-function\[8104\]:0x444f24,at invoke_viii (https://rdsgw.remotedomain.com/rdweb/webclient/librdp/html/librdphtml.c4af5b60.js:86:253457),at https://rdsgw.remotedomain.com/rdweb/webclient/librdp/html/librdphtml.4fe32847.wasm:wasm-function\[1465\]:0xdee11,at https://rdsgw.remotedomain.com/rdweb/webclient/librdp/html/librdphtml.4fe32847.wasm:wasm-function\[1808\]:0x10fbad,at invoke_vii (https://rdsgw.remotedomain.com/rdweb/webclient/librdp/html/librdphtml.c4af5b60.js:86:253620),at https://rdsgw.remotedomain.com/rdweb/webclient/librdp/html/librdphtml.4fe32847.wasm:wasm-function\[7510\]:0x389a61,at invoke_vii (https://rdsgw.remotedomain.com/rdweb/webclient/librdp/html/librdphtml.c4af5b60.js:86:253620),at https://rdsgw.remotedomain.com/rdweb/webclient/librdp/html/librdphtml.4fe32847.wasm:wasm-function\[729\]:0x664a0,at OnMessageCallback.OnMessageCallback$Invoke [as Invoke] (eval at new_ (https://rdsgw.remotedomain.com/rdweb/webclient/librdp/html/librdphtml.c4af5b60.js:86:202948), <anonymous>:9:1),at Worker.<anonymous> (https://rdsgw.remotedomain.com/rdweb/webclient/librdp/html/librdphtml.c4af5b60.js:86:26127)
2022-09-06T15:33:38.838Z WebSocketTransport(NORM): Connection close initiated for url=wss://rdsgw.remotedomain.com:443/remoteDesktopGateway?CorId=%7Bf7246328-ddb2-4b17-aff2-050bd5f90000%7D&ConId=%7B1121a2c2-0037-4249-ba7a-b309779c226a%7D&ClGen=HTML%3D1&ClBld=Type%3DRdClient%3B%20Build%3Dprivate&AuthS=SSPI_NTLM, code=1000, reason="NormalClosure(1000)"
2022-09-06T15:33:38.839Z GatewayTransport(NORM): GatewayTransport closed.
2022-09-06T15:33:38.841Z [Connection] Disconnected