Enabling options at Control Panel > Terminal & SNMP > Terminal allows your Synology NAS to support Telnet and SSH command-line interface services. You can also change the security level of the SSH encryption algorithm.
A variety of encryption algorithms with different security levels are used in securing SSH connections. You can decide which algorithms are used to best meet your needs.
Some models support hardware acceleration for certain encryption algorithms. You can check the option Only use hardware accelerated ciphers to improve the transfer speeds of SSH-related services, including encrypted Network Backup and SFTP services. In the advanced page, algorithms capable of using hardware acceleration are shown in red.