You can go to /intel/euclid/config/settings.ini, there you can change the ROS_MASTER_URI.
Make sure you restart the oobe-init service, as you mentioned after doing so.
We'll check why it is "scrambled" when you use the web as well.
The site below describes a method for changing ros_master_uri on boot-up of your PC (someone claimed the master URL cannot be changed once ROS is running).
Thanks! That did the trick.
Glad that majdS' answer was able to help - thanks majdS! It was a more useful answer than mine.