Wireless Joint

I have a WG1608 (16M) with RM520N-GL and am seeing far less than expected cellular performance. I live about 1.5 miles from a T-Mobile UC tower. My SIM in a MR6150 I see ~800Mbps download/20Mbps upload. The same SIM in the WG1608 the most I see is 250Mbps download/30Mbps upload, router load is ~1.1 ...

My speedtest can max only 250 down & 50 down. I want to try updating module firmware as it might improve.