I've recently upgraded from a 10 Mbit/sec DL speed to 100 Mbit/sec DL speed from my ISP. All of my other devices which includes my phones and television have noticeably improved. The speedchecks on the phones are matching close to 120mbps, yet my laptop won't exceed 4.5mbps. The Network adapter is an Intel(R) Dual Band Wireless-AC 3160 and is updated. I've also purchased a Netis USB wifi adapter and the DL speeds haven't changed either. Upload speeds are at 10mbps on all devices including the laptop.
If it is happening with this Netis adapter as well, it isn't an issue with the 3160 module. I would be looking at your wireless router configuration.
Well, that all depends upon what wireless router you have and what it supports. If it was, for example, only connecting using the 2.4GHz band or only connecting using Wireless-N, that would explain it.