@ArcherC8 Thanks for the reply. I have toyed with some of the settings, haven't gotten to trying specific channels yet. I was asking in a more general sense, i.e.,

the AC 7265 is known not to work. Wi-fi adapters are cheaper than I realized, I'll consider replacing mine. 

ArcherC8 wrote

If other devices can connect to both bands then one would think the issue is with that specific device not the router. Try deleting (forget) that network and re-establishing it. That may correct the issue. Also try specific WIFI channesl and band widths for that band.

@JoeyD 

There are not any compatibility issues. Might be worth checking if any new drivers may be availble for your adapter.