Hello I tried the same - document server on Xenial (16.04) but after restart I get only 502 bad gateway.
I have three indipendent servers with same failure.
But kernel on Xenial is not in support list http://onlyo.co/1PABPEI
If I tried the same config (with little change I use nodejs v7) on Trusty (14.04) after restart - everything was OK.
I don't think that kernel is the bloblem, it was changeg a lot of packages.