The driver has been updated via WiFi_20.10.2_PROSet64_Win7, and all of Intel's recommended settings are checked off in the Device Manager.
According to an inSSIDer scan, the both the 2.4 ghz and 5 ghz signals are detected, but only the 2.4 ghz network can be joined. The AC 3160 is installed in a Lenovo Thinkpad E450 running Win7 Pro 64 bit. The router is a Netgear 6230.
An iPhone SE will connect to the 5G network, so the problem is definitely in the network adapter.
What am I missing here? Please help!