How to connect to a machine via rdp from a different subnet?

Question

Computer networks

In general, there is a vlan network 192.168.55.__ inside it I had to put an old tp-link model router (almost no adequate settings in it. Far from blissful Mikrotik) 2 more pc are connected from it via lan. One of them (ip: 192.168.100.1) needs to be connected from the external network via rdp.
The point is to log into windows from different accounts and work at the same time. So AA and TeamViewer are out as far as I know.
The router has a static ip (192.168.55.32)
Gateway 192.168.55.251
Mask /23
DNS: 192.168.55.1/2
Firewall in the router (more precisely, a few rules from the firewall, you can’t call it otherwise) is disabled
Settings for bridge forwarding and many others were not found .
Problem: cars from the subnet see ip from the external network. They ping, look at arp. But machines from the external network do not see ip behind the router (which is probably logical)
When you disable the dhcp router, the network disappears on computers connected via lan. Even if I set network parameters manually.

Answer 1

turn off dhcp on the tlink, and turn on the cable from network 55 not to the wan port, but to lan,
get such a switch

Answer 2

I have several networks, I have an intermediate machine (Debian 9) that looks into these networks (zabbix), where rinetd runs.
Through it, I forwarded the necessary ports (RDP, IPMI) to the desired network.