If you combine Remote Desktop with Pertino, a cloud-based VPN (free for up to three devices— read our review), your remote PC will be reachable without all the firewall and IP address hassles.

3. After opening Remote Desktop Connection, you will need to enter the Computer that you want to access. This can be in the form of an IP address, such as 164.111.65.189 (yours will be different) or ...

If you want to enable Remote Desktop Access with xrdp on Raspberry Pi to connect to it using any device of your choice, see this tutorial.