@IrvSp Thanks for your reply. So far via terminal commands I am able to see that my (2017) iMac has a Broadcom BCM43602 wifi chipset. I suppose it's possible that the speeds I'm seeing are as fast as...

@Pianophile > I removed and re-added my preferred network, and all I get is 284/169 up/down. Following a tip I found elsewhere on the net, I reset the AX6000 to factory specs, and set it up again,...

@IrvSp > Well, do you have AC or AX wireless devices? Need those to probably go over 300Mbps. Yes, my iMac is my primary device, and it is connected ot the router via 802.11ac, usually at a Tx rate...

Using an Archer AX6000 hardward v1, latest firmware. Enjoyed full speed of my 300Mbps connection (typically in the high 290s up and down), and was looking forward to a service upgrade to 500Mbps...