Hi, I installed a couple of times JDownloader2 in my Qnap Nas with the same result:
No internet connection on other home devices while connecting to MyJDownloader Nas web interface and downloading files to my Nas.
In order to restore internet connectivity, I had to reboot my ADSL modem/router after download's completion.
I searched for a posted solution without success till now.
I am wondering if this is due to Router specific settings, Qnap settings or MyJDownloader web interface settings.

Any explanatory comment for solving it, is welcome.