Connectivity issues since receiving new modem

I have placed at least 15 calls to Xfinity over the last couple of weeks.   I was given  a new moden and since then have had connectivity issues over  and over and over again.  I am also having issues with connectivity to my printer.  The 800 number is useless.   I'm VERY CLOSE to cancelling my account if I cannot get proper technical support .  iThis is a first after many years as a happy subscriber.