@IrvSp 

Don't really follow your reasoning here. I understand that switching to the 2.4GHz band likely had to do with distance from the router. That is working as desired. Having a single SSID seems to be working exactly as I want, at least so far, with the potential exception that load balancing across the bands might be better even if it forces more devices onto 2.4GHz

@gcmn 

Well, 'Smart Connect' I don't think works for everyone. It is good if you have no idea why a device should be on one band or another. Smart Connect handles the band selection, but it does have drawbacks in doing so, and in some cases, this depends on the implementation. Smart Connect chips have 'options' and the router vendor may or may not enable them all.

Look at these two threads,

https://community.tp-link.com/us/home/forum/topic/195526

https://www.quora.com/What-are-the-benefits-and-disadvantages-of-using-different-SSIDs-for-2-4-ghz-and-5-ghz-bands-on-the-same-router

Basically is comes down to 'WHY' you would choose a different band for different devices AND will Smart Connect make the same decision?

Consider ALL the devices you have? Do you have a dual-band or tri-band router as that too plays into the equation.

For a dual band you'd want ALL your 'slow' devices (today you might have an older G and newer N Speed 802.11 devices) and your 'faster' ones (AC or AX 802.11 devices).

G would max out at 54Mbps, N, 300Mbps, AC and AX probably as fast as your ISP delivers speed.

So you'd put the slower ones on the 2.4Ghz band and the faster ones on the 5Ghz band(s for a tri-band router).

Now, what happens when you move the N device over to the 5Ghz band or an AC to the 2.4Ghz band?  As the router 'operates' it goes to the speed the device can handle... now devices are not active all the time. Let's look at possibly and N speed on 5Ghz STREAMING a video. That is constant operation basically. The 5Ghz band will slow down feeding data to the faster devices as long as it is in operation, at least theoretically.

Now consider TP-Links implementation,

See these two TP-Link pages:

https://www.tp-link.com/us/support/faq/2595/

https://www.tp-link.com/us/solution/smart-connect/

That second one implies it does LOAD LEVELING... so that means you could have a mixed band of devices... Theory being 20 devices on the 2.4Ghz band and 4 on the 5Ghz band, let's even it so there 'could' be less contention for TCP/IP.

As far as I'm concerned, I 'think' I know better than the router and how to manage the devices I assign to my bands. If you don't feel you do, use Smart Connect. Not trying to be rude or arrogant, just I want control. That said, maybe Smart Connect would work just as well for you, depending usage and devices?

You can test the 'theory' out easily. Put two devices, one N and the AC/AX on the 2.4Ghz band and have both start a large d/l and see the speed of the d/l on each device... probably the same. Now only use the AC/AX device, bet it d/l's faster. Do the same on the 5Ghz band.

Don't use Streaming as an example, most work well at 10Mbps down which all bands would deliver probably unless there is significant loads at the time on the router.

@IrvSp Thanks! Yes I'm certainly not trying to claim that Smart Connect is great for everyone. My point was just to say that the particular pathalogical behavior of moving all devices to 2.4 GHz (which is definitely less smart than what I could do) doesn't appear to be present in combination of hardware/firmware/software I have. That was what this thread was originally about and I just wanted to add a data point for future folks trying to decide if Smart Connect is right for them. For now, Smart Connect is doing a reasonable job and I'm able to max out my ISP speed with my laptop and I didn't have to go around and fiddle with all the smart devices in my house.

But, thanks to your suggestions, maybe I'll spend some time playing with it and see if I can come up with something better via manual assignment :-)