[manül]

because of some Firewallthings in the office I wanted to change the Streaming Port (7522) to another.

If my mind isn't fooling me, in an earlier version there was the possiblity to change this within the addon.
Can I do this with your version also? (maybe hardcoded and not over the GUI)

Yes, there was an old setting. But newer RS versions provide the streaming port as part of their API. So just change the port in the RS configuration interface and everything will automagically work