Resolution
To change port for SiteStudio if it's stand-alone or integrated with other control panels:
1. Change port in the SiteStudio_home_directory/jakarta/conf/server.xml file
Usually SiteStudio_home_directory is /home/SiteStudio
2. Go to the SiteStudio home directory and run:
./ss.sh setup
Enter IP and new port at the first step of the wizard and leave other
configiurations without changes.
3. Restart SS
./ss.sh stop
./ss.sh start
4. Check if everything is working correctly