When you link a Lansweeper Classic installation to a Lansweeper Platform site, one of the prerequisite checks confirms that the machine hosting your web console has TLS 1.2 enabled.
Why this check runs
To secure communication between your installation and Lansweeper Platform, the connection uses the TLS 1.2 cryptographic protocol. If your web server doesn't have TLS 1.2 enabled, communication with the Platform fails. Computers running a modern operating system usually have TLS 1.2 enabled by default.
Resolve a failed check
If the web server TLS 1.2 check fails, enable TLS 1.2 on the machine hosting your web console. You can find instructions online and in Microsoft's documentation.
Edit TLS settings in the machine's registry carefully. Incorrect changes can stop the machine from working.
When all prerequisites pass, you can link your installation to a site.