I have just had Vodafone 4G LTE RBI installed and while it's a mile better than my end-of-the-line ADSL, I was surprised to see that they installed only a single enclosed antenna. One of these: http://www.gowifi.co.nz/antennas-1710-2100mhz-directio/11dbi-wideband-lte-broadband-directional-antenna.html
4G LTE requires TWO antennas to perform properly (MIMO - multi-in, multi-out). The antenna used is ideal, but there needs to be two of them, pointing the same direction, one vertical plane, one horizontal plane.
Good article here: https://www.youtube.com/watch?v=cB1v_YDqjOk
I suggested this to the contractors who said they have been doing installs for 2 years and have never used two antennas, and they had never heard the term MIMO. It did make sense to them since there are two antenna ports on the B315 router. Can't blame them though as they are working under very tight directive/contracts.
Fortunately they were willing to lay a second cable for me (at my cost) and I bought and fitted a second antenna myself.
I am 13km from the current tower well out of line-of-sight (a nearer tower has yet to have 4G enabled) here are the results:
One antenna: average 28-32mbps down / 6-8mbps up
Two antennas: average 45-48mbps down / 10-11mbps up
Seems a shame that Vodafone would skimp on the antennas after spending so much on the rest of the infrastructure.
Do yourself a favor folks and ask your friendly installer to put another cable in for you, then jump online to gowifi and get yourself a second antenna (or, Vodafone stop being so tight and install two for your customers!) . - The router will (should) automatically select external antenna for both ports, but you can set this manually as I did via the admin screens.