This might be basic, but I don't know the answer... Given a router and a client, both having 2.4G (slower, more range) and 5.XG (faster, less range) frequency radios (and both named with the same SSID on the router), what determines which frequency gets used by the pair? The client or the router? Based on what? (Signal strength? Data throughput?)
I was thinking router, but I was told it was the client (by a system integration "Engineer" here at my employer.)
It depend on driver. Check your WNIC configuration on client side, there should be option which band you want prefer.
The client chooses the SSID or WAP it tries to link with, usually by SSID. If the same SSID is present on multiple bands (multiple radios) it likely chooses the one promising the highest link rate which depends on signal strength.
It is Bandsteering a feature of the gateway which would force the client to associate. There are many incarnations of BS but the simple one is AP would simply blacklist client in on of the client or it will not accept probes in one band. The decision to steer could be based on Phy Rate, Number of clients in the band, channel utilization...etc. On some occasions it is entirely up to the client.
