Guide info comes from the router to the box either thru coax if its a VMS or Wifi or Ethernet or coax if its an IPC . I suggest powercycling your router and your box, not just rebooting them. Do the Router first, then the box. Also check all the coax connections.
This happened to me Friday night guide on both TVs stopped working. Spent Saturday with tech support without a fix. I rebooted everything and he reset everything with no change. He figured it was a wiring issue and setup a service call. I called tech support Monday morning and talked to a different guy who thinks it is an issue on there end. Each box is showing a good connection and no issues. He asked we give them a couple days to see if it fixes it self.