Same problem here. I even bought a usb3 to giga netwotk. Same problem! When I playing VOD and when I try some 4K movies its buffering all the time.
4k tv streaming will even not start! I have a 500/500 line, so the conection is not a probklem. Now i bought a MAG 322 and all works perfect even with 4k streaming with live tv and VOD. Sorry, but I think the hardware in the Formula is to weak.