I've got a Sierra Wireless Airprime MC7354 module, supplying a cellular communication to my x86 - running Ubuntu Server 14.04.
By default, on module boot, it searches for an LTE network connection, and if fails - it falls back to 3G.
Though I'm supplied with several Sim cards, from different providers, all are LTE compatible (works great on my phone) - I can only get a 3G network with Ubuntu (no LTE).
Ideas anyone?