Checked the Logs

C:\Windows\LTSvc\LTErrors.txt

LTService  v240.223	 - 6/27/2024 1:37:21 PM	 - WebRqst: https://server.domain.com/LabTech/Agent.aspx?DEPS : SendFailure : The underlying connection was closed: An unexpected error occurred on a send. :   inner: Authentication failed because the remote party has closed the transport stream. : :::
LTService  v240.223	 - 6/27/2024 1:37:24 PM	 - WebRqst: https://server.domain.com/LabTech/Agent.aspx?DEPS : SendFailure : The underlying connection was closed: An unexpected error occurred on a send. :   inner: Authentication failed because the remote party has closed the transport stream. : :::
LTService  v240.223	 - 6/27/2024 1:37:27 PM	 - WebRqst: https://server.domain.com/LabTech/Agent.aspx?DEPS : SendFailure : The underlying connection was closed: An unexpected error occurred on a send. :   inner: Authentication failed because the remote party has closed the transport stream. : :::
LTService  v240.223	 - 6/27/2024 1:37:29 PM	 - WebRqst: https://server.domain.com/LabTech/Agent.aspx?DEPS : SendFailure : The underlying connection was closed: An unexpected error occurred on a send. :   inner: Authentication failed because the remote party has closed the transport stream. : :::
LTService  v240.223	 - 6/27/2024 1:37:32 PM	 - WebRqst: https://server.domain.com/LabTech/Agent.aspx?DEPS : SendFailure : The underlying connection was closed: An unexpected error occurred on a send. :   inner: Authentication failed because the remote party has closed the transport stream. : :::
LTService  v240.223	 - 6/27/2024 1:37:34 PM	 - WebRqst: https://server.domain.com/LabTech/Agent.aspx?DEPS : SendFailure : The underlying connection was closed: An unexpected error occurred on a send. :   inner: Authentication failed because the remote party has closed the transport stream. : :::
LTService  v240.223	 - 6/27/2024 1:37:37 PM	 - UNCompress Error: Index was outside the bounds of the array.:::

What I tried to do

• Confirmed TLS 1.2 Is enabled both Sides ( Server and Client )
• Confirmed .net 4 is operating at tls1.2 ( SystemDefaultTlsVersions \ SchUseStrongCrypto ) which is does by default
• Confirmed I can access https://server.domain.com/LabTech/Agent.aspx?DEPS via the Web Browser of the computer

I then double-checked the Ciphers on our server

Looks like these are not enabled on server 2022 by default

We needed to update the Ciphers on Connectwise Server to fix this