hmm I would suggest there's something more to this than "Internet cut off". There's pretty much no chance you could cut off all connectivity from a building in the heart of london (https://www.google.co.uk/maps/place/Embassy+of+Ecuador/@51.4...)

From that location you have Base station's covering all 4 major UK mobile networks and I'd guess a large number of wi-fi hotspots.

So to "cut off" internet access, you've got to cut all BT lines in and out of the building, block all 3/4G signals all round the building and block each and every wi-fi band around that area, without smegging up all the frequencies in a very central part of london, right next to large shopping areas like Harrods.

you cant' just cut off devices known to belong to Assange, as anyone can buy a 4G router with cash from a shop in London which isn't easily attributable to him.

oh yeah and I forgot there's the satellite internet bit they'd need to block too.