Thank you for your question.
A remote-access VPN enables users who are working remotely to securely access and use applications and data that reside on the server.
For your case, I would recommend choosing one of these VPN solutions for Remote Access:
OpenVPN - is an easy to set up virtual private network system that implements techniques to create secure point-to-point or site-to-site connections in routed or bridged configurations and remote access facilities. To configure OpenVPN you will need to create a server on your router (here is an example of how to do it: https://wiki.teltonika-networks.com/view/OpenVPN_configuration_examples) and set up a client on your Windows/Linux machine. For Windows: https://wiki.teltonika-networks.com/view/OpenVPN_client_on_Windows For Linux: https://wiki.teltonika-networks.com/view/OpenVPN_client_on_Linux
L2TP over IPsec - L2TP connects the networks of server and client, IPsec provides the encryption for the L2TP tunnel. Here is a configuration example on how to set up it: https://wiki.teltonika-networks.com/view/Connecting_to_the_office_network_remotely_from_your_home_via_VPN_(L2TP_over_IPsec)_using_RUTX
ZeroTier - is open-source software that can establish Peer to Peer VPN (P2PVPN) connections between various devices running various operating systems. It also provides network management possibilities such as routing and creating firewall rules. Here is a configuration example on how to set up ZeroTier VPN: https://wiki.teltonika-networks.com/view/ZeroTier_Configuration
For the site-to-site VPNs, they are more being used by companies that want to connect to multiple remote offices. To create a site-to-site connection you can choose any of these VPNs and their combinations: OpenVPN, GRE, IPSec, PPTP, L2TP, SSTP, STUNNEL, DMVPN, Wireguard.
For example here is the OpenVPN configuration example: https://wiki.teltonika-networks.com/view/Connecting_two_same_subnet_office_networks_using_OpenVPN_bridge_(TAP)_on_RUTX
And here is an example combination of GRE over IPSec: https://wiki.teltonika-networks.com/view/Setting_up_a_GRE_over_IPsec_tunnel_between_RUTOS_devices