fitful(characterized by sudden bursts of activity with periods of inactivity in between, see also: intermittent; irregular) adjective [UK: ˈfɪt.fəl] [US: ˈfɪt.fəl]
sporadic(rare and scattered in occurrence) adjective [UK: spə.ˈræ.dɪk] [US: spə.ˈræ.dɪk]My connection has sporadic problems. = La mia connessione ha dei problemi sporadici.