I have the same problem. No matter if I’m using BOINC version 6 or 7, the BOINC manager fails to connect to the client (which itself is running properly in the background, as seen by systemctl status boinc-client). It seems to try and spawn its own boinc process and fails repeatedly, then says “disconnected”. Though if I cd to /var/lib/boinc and run sudo boinccmd --run_benchmarks, the benchmarks do get run. So at least that’s something, although not quite ideal…