Louise Mensch tweeting about it was a server located in Trump tower that was under investigation.
Belongs to a Bank. With Russian connections.
One presumes that's why they can say it wasn't a tap on him or the tower, but a server.
On a lighter note, JK Rowling reckons he is actually Vicki Pollard and now I'm ready Trump Tweets in a broad Bristolian twang. It's scarily accurate.