Access control lists?

[tigerdog]

I am setting up a VPN from a less secure location to one that's a bit more sensitive. I initially planned to go the other way but a double-NAT at the remote end forces this configuration. I need to limit traffic from the less-secure location with the VPN client, restricting to a single IP address and UDP port at the more secure facility. Is there a way to do this? Equipment is
RT-AC87U with 380.9 more secure site
RT-AC68U with 390.0 less secure site

Also, is it possible to display the internal routing table?

Many thanks in advance for any help that might be offered.