This seems overly complex. If this is about accessing webUI of your torrent client (or any other type of service/app) remotely, from outside of your home network, simply use SSH tunneling. It is by far the most secure solution since it does not require you to open extra ports. And it’s suprisingly easy!
You simply use the same port you use for SSH.
It allows you to connect quickly via SSH but also add SSH tunneling. No need to open extra ports or expose your Torrents WebUI to the internet. Very easy and probably the safest, most secure method!
For Android devices, I would recommend Termius but there are plenty options. It’s like Putty but on a phone and more user friendly. After you connect via Termius app, you can access the webUI of Transmission (or Deluge, if you prefer) or use an app like Torrnado (which I highly prefer since it has way more options than the webUI of Transmission).