Got the same problem previously when I got an emailed from Synology that my NAS got disconnected several times even after I rebooted the Router and Modem. Just called 123 and talk to the Rep. (better if you at home that time and you can call them even at night). They will change some setting that suit to your location and will ask you to reboot you modem and router. So far so good no more disconnection or lag.