Hi. I have recently installed OSMC on a pi3. I have also installed the transmission app from the OSMC store. While setting up my sickrage install I discovered a problem accessing transmission rpc. This led me to try and change the settings.json ”rpc-whitelist enabeld” setting from true to false via the command:
sudo nano /home/osmc/.config/transmission-daemon/settings.json.
As per instructions found on this site I did so while the transmission service was stopped. However after restarting the service the file is constantly altered back to its original settings despite double checking that the changes to the file were successful before restarting. I have tried stop/starting the service by both “my osmc” and with the commands:
sudo systemctl stop transmission
sudo systemctl start transmission.
I have also reinstalled transmission via:
sudo apt-get purge armv7-transmission-app-osmc
sudo apt-get install armv7-transmission-app-osmc
I am unsure how to proceed from here and welcome any and all suggestions! I am a fairly inexperienced Linux user but can follow instructions and use Google 
Hopefully I’m just missing something really obvious.
Hi @mgirando!
After browsing this forum for a while, as well as transmission-daemon-specific and kodi-specific threads, I finally figured out what was going on:
When you run sudo systemctl start transmission, the instructions located at /lib/systemd/system/transmission.service are executed. In that script, which most likely comes with the Transmission install from the OSMC app store, the option --allowed *.*.*.* is specified. And it seems that simply specifying that option causes the settings.json file to be updated.
My solution to this problem
sudo systemctl stop transmission
sudo vim /lib/systemd/system/transmission.service
# Remove the --allowed option or set it to what you like
sudo systemctl daemon-reload
vim .config/transmission-daemon/settings.json
# Disable rpc-whitelist-enabled
sudo systemctl start transmission
Your configuration should now be active and not overwritten.
Note that this is not a very robust solution since /lib/systemd/system/transmission.service is likely to be overwritten at the next app update.
The solution to the problem I was originally trying to fix
I was actually trying to setup the Transmission RPC interface to be accessible from the outside world. I went through the NoIp configuration, port forwarding on my router, etc… But I could not reach the Transmission web interface through my NoIp domain!
After trying out many fixes (firewall, etc), it turned out the problem was somewhere else: I was trying to access it from my local network. Connecting to a VPN (outside the local network) and accessing my NoIp domain worked! So connecting from the outside world was actually working from the start, I was just not in the outside world.