GUI RPC bind to port 31416 failed: 98

From BOINC Wiki

This error happens when the user has no permission to use the RPC port number, or forgotten to allow it through the firewall.
Happens in combination with Gstate.init() failed, error code: -180

To set BOINC to use a specific port number, one different from the default 31316, do:
boinc --gui_rpc_port N, example given boinc --gui_rpc_port 37777, this starts the BOINC client with TCP port 37777.

If you don't want to use any GUI to check on this BOINC from a remote location, you can also start BOINC without any GUI RPC:
boinc --no_gui_rpc