Just checked that I can connect RD to a Windows machine using the egress range from an external client Android phone on 18.5. As mentioned, I did have to port forward through NAT to the ingress/egress gateway on 51822. I can also reach this machine running the windows 18.5 netclient using the netmaker dns name and the netmaker network 1p address. The point being that 18.5 is definitely functional so it is worth persevering