How to remotely connect to a computer (to 1C) behind NAT, without TeamViewer-like software?

Question

1C

1. The first router of the owner of an office building. It receives a dynamic IP from the provider and distributes the Internet to everyone.
2. The second router behind NAT from the first is in our office.
The office has a computer with 1C, I want to periodically connect to it remotely.
However, the desktop cannot be occupied, so something like TeamViewer is not suitable.
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Possible solution:
1. Build a VPN tunnel, you can use openvpn, or tunnel operator https://ngrok.com. I liked tinc.
2. Configure the server with a terminal (patch 7-ku so that the terminal server works)
3. Connect via RDP and log in as a different user.
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Continuation of the topic:How to connect two networks behind NATs without a dedicated IP and port forwarding?

Answer 1

The first option: configure ddns and connect via rdp under a different user. (On the Internet, you can search how to allow simultaneous connection of users)
The second option: something like dameware.