When viewing recent lighttpd-access.log logs in a CCU connection one can note the following connection track:

127.0.0.1 127.0.0.1:1999 - [31/Jan/2025:12:05:37 +0100] "POST / HTTP/1.1" 200 132 "-" "Go-http-client/1.1"
127.0.0.1 127.0.0.1:9292 - [31/Jan/2025:12:05:37 +0100] "POST /bidcos HTTP/1.1" 200 123 "-" "Go-http-client/1.1"

These connections originate from CCU-Jack. However, when CCU-Jack is running on the CCU/RaspberryMatic itself it would be more appropriate/good to perform the interconnection between CCU-Jack and all the other interface processes (HMIPServer, rfd, etc.) using direct non-proxied connections. So for HMIPServer (HmIP) connection CCU-Jack should connect to 39292 and for rfd (BidCos) to 31999, etc. However, there does not seem to be a possibility to specify/override these ports in the ccu-jack.cfg file or somewhere from the CCU-Jack configuration page. Even better would be if CCU-Jack would automatically prefer to perform direct connections without involvement of the lighttpd proxy.