Mini box in bedroom goes crazy

Have Comcast Xfi gateway and X1 tv box in main room.  Mini in bedroom.  First few months excellent operatiog with no complaints but suddenly getting "having problems connecting to the internet" on my tv.  Why do I need the internet if the coax comes from the wall into a splitter with another coax from splitter to Xfi and to X1?  Then last night I was woken up by the mini box in my bedroom flashing the green light for a short time.  Later was watching tv on the X1 box and it suddenly went blank.  Had to call Comcast and was told "your X1 box is offline, unplug".  After a while it came back on but what's going on?  Had a actual service tech out last Saturday who checked the signal, connections and even opened the wall plate to make sure the connections were tight.  He did install a POE MOCA filter since I had to do a self install and that's not a part that is given.  Again...what's up?