X1 box lagging

I’m having the same issues with the lag.  The extra frustrating part is my X1 4K box went bad.  They came to my house and down graded the box and now I have a huge lag.   I call to get the 4k box and was told because I do not have the xfinity modem they will not send a 4k box.   

I do a nightly restart for the days I want to watch TV.