Nighthawk MR1100 Slow Speed

I have a MR1100 on AT&T and I am in a rural setting about 1 mile from the cell tower.  I have been

experiencing speeds all over the map.  First thing the morning download was 60 Mbps and a hour or

two later it was 13 Mbps.  I have four bars on the router.  He are the diagnostic readings:

RSRP -95dbm

RSRQ -12dm

LTE B30 radio band

I have a directional antenna I can install outside but I am skeptical on what it will improve.