If you have a Synology NAS, have the VPN Server installed, configured OpenVPN and use an Apple Macbook with OSX with Tunnelblick as your VPN client, you've probably seen this message:
Warning: This VPN may not connect in the future. The OpenVPN configuration file for 'Undercity OpenVPN' contains these OpenVPN options: 'comp-lzo' was deprecated in OpenVPN 2.4 and removed in OpenVPN 2.5 You should update the configuration so it can be used with modern versions of OpenVPN. Tunnelblick will use OpenVPN 2.4.4 - OpenSSL v1.0.2n to connect this configuration. However, you will not be able to connect to this VPN with future versions of Tunnelblick that do not include a version of OpenVPN that accepts the options.
All you have to do to ensure compression is enabled, through the config file is to replace one line in the ovpn config file you're using. Replace the line with
You won't have the warning message show up in the Log window after that.