With the 2 sticks I tried, the first was not recognised, and the second was recognised (ie the z1 knew what device it was), but just sat at "connecting" without going any further.   I've since given up on the USB port and have now connected the 4G stick via a 3rd party 4G router and into the WAN port.  Not ideal, but as I mainly want it for the 4G connection, this works.  If I was using it in a failover situation, then in theory it should happen that rarely that I would just manually patch it over without it being too much of an issue.   Al. ... View more