If you continue to get error messages like this: "The request was aborted: Could not create SSL/TLS secure channel" then first thing you can try is to switch back to Connectwise API 2.0. To do this, open our integration tool's configuration screen and in the section that connects to Connectwise pick API 2.0 instead of 2.5. With this, you will need to enter your username and password to Connectwise as before. I believe it will not bother you with that message anymore.
However that is a temporary solution. The permanent solution which we strongly encourage to do is to upgrade your Connectwise server (cw.yourserver.com.au) to TLS 1.2. We believe you have TLS 1.0 installed there which is deprecated as of 30 June.
TLS is not a Connectwise feature. That is installed on the web server where your Connectwise site lives. So you need to speak to your server engineers and check what version of TLS you have, and if you are still on 1.0 then they'll need to follow procedures to upgrade to 1.2. We don't have documentation on how to do that, and the steps are different for each type of server. You can find plenty of information about the deprecation of TLS 1.0 on the web and how to upgrade to 1.2.
So, back to why you are getting this message now and not before: version 2.5 of the Connectwise API enforces the use of an updated version of TLS. I think version 2.0 of the API still allows you to use the old TLS... but unsure if that will change, so best to upgrade TLS anyway. It's in your best interest anyway to avoid being victim of some vulnerabilities.