A lot depends on the CAT rating of your mifi or router, my cat 4 mifi with external antenna is not as fast as my cat 6 mifi without an external antenna, I am in the process of buying a second hand CAT 12 router to try out, the higher rated routers can amalgamate data from more than one band giving you more bandwidth and therefore more speed. I'll report back with results once it has arrived and i've tested it.