WiFi Connection to Desktop Drops Intermittently

After receiving a new Xfinity modem, for some reason the WiFi connection to my desktop PC drops intermittently. I can be working for several hours with no issue, and then all of a sudden the WiFi connection drops. I cannot just reconnect to the network, and I have to reboot the PC in order to connect again. I'll then be good for another couple of hours, but the connection will invariably drop and I'll have to start the whole process of rebooting over again. Never had this issue with my old modem, so I feel that is somehow the problem. Any thoughts?