If it's something you really, really need (and I still can't figure out the use case for this) and you have a computer on the same network that you can
SSH to, I've successfully used
PuTTY and port tunnels. I was just playing with tunnels at the time, so all I did was to see if I could get the "active_app" on my Mother's Roku. I don't think you're going to get your phone's remote control app to work this way, but you can query things via the port 8060 web interface and I'm guessing using cURL to issue ECP commands should work.
-JT
Roku Community Streaming Expert
Help others find this answer and click "Accept as Solution."
If you appreciate my answer, maybe give me a Kudo.
I am not a Roku employee.