There are a number of available options.
As for other options, there is the SSH protocol. OpenSSH
(ssh(1)) is part of OpenBSD's base installation.
VPN (Virtual Private Network) solutions also exist.
OpenVPN is also an application which has been ported to other Unix-like operating systems.
IPsec is also part of OpenBSD's base installation. A number of manpages will need to be studied; starting at
ipsec(4) is a good beginning. Configuring IPsec is perhaps more challenging than OpenVPN, but IPsec
(as a protocol) is integrated into OpenBSD's kernel. OpenVPN is a userland third-party application.
One of the values of VPN solutions is that this addresses
"road warriors" who may be connecting to servers from
any IP address. With SSH, you will need to decide how port 22
(or whatever port you choose to use...) will be exposed to the Internet.
The other options I have mentioned are based on fundamental protocols, & may give you more latitude in terms of how you connect remotely.