SQL Server Management Studio cannot connect because of common algorithm
One issue that can cause this is if TLS 1.0 is disabled on the client as part of a security hardening process.  Since the version of SQL Server you are trying to connect to doesn't support a version of TLS that is enabled on your system, the connection fails.
If you can't upgrade SQL Server, the only solution is to enable TLS 1.0 on the system where SSMS is running.  This can be done by modifying the appropriate registry settings specified in Transport Layer Security (TLS) registry settings

Registry path: HKLM SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL\Protocols
To enable the TLS 1.0 protocol, create an Enabled entry in either the Client or Server subkey as described in the following table. This entry does not exist in the registry by default. After you have created the entry, change the DWORD value to 1.