@Interdimensiona 

One thing to try is to delete (forget) the network on the device, power cycle it, and then set it back up again as that helps some who just changed routers.

Thank you for the suggestion. I gave it an attempt and "forgot" (which forced a reboot) and then had to re-enter the network password.

Sadly, t here was no change in behavior.

Later on I got the extension cord out and was able to place the Roku closer and on the other side of the router. Boy did that make a HUGE difference. The network strength managed to make it all the way to "Good" and there is apparently no way to get the signal strength to "Excellent" with these 2 pieces of hardware because it is 1 foot away now on the right-hand side as I look at it.

The bandwidth it predicts I can consume is in the mid 30 MBs. So a huge 3-10x improvement depending on how poorly it was going on the other locations I had attempted.

Does any of this sound abnormal to you?

I guess since I have other tech that succeeds on the 2.4GHz band I have no one to blame but Roku's player. It would be *nice* if there were other configurable things I could try with the router since there are SO MANY knobs in the tp-link device but it isn't clear what might help.

Keep the ideas coming if anyone else stumbles across this thread. Thanks again

@Interdimensiona 

A few more things:

• Some devices do better with specific band widths. So You should try different WIFI Bandwidths.
• You could also try different WIFI channels.
• As I understand, at about 5-10 feet is where the sweet spot is for WIFI
• Are you using different SSIDs?
• Are you using any QoS?
• Are you using a VPN?
• Are your antennas attached good. May want to try switching them if they are detachable.
• Are you using the power adapter that came with the router.
• Router location does matter as small changes make a difference. But that will be in play when you have the router and device in the normal locations.
• Has anything on the device changed about the same time as the router change such as a firmware/software upgrade?

Thanks for all these thoughts. Here's my reactions:

• This Roku can only use the 2.4 GHz bandwidth
• I tried channels 1, 6, and stuck with 11 since it seemed to perform the least worst. I did not try others because of the Roku article linked in my og post.
• 5-10 feet is interesting. I did not try moving the device further away and it would complicate usage but I will consider it!
• I am now using different SSIDs. Do you think that could help a device that only operates on 1 bandwidth from a dual bandwidth router?
• I am not using QoS - should I? The problems were existing even when it was the only device using bandwidth in the house
• I am not using a VPN for the Roku nor at the router level
• I did not check the antennas or thought about switching. Thanks for the idea!
• Yes, I'm using the original power adapter for the router.
• I actually attempted to update the firmware of the Roku but only after we were having problems. There were no updates available.

The new location closer and on the other side of the router worked really well last night so unless you recommend turning ON QoS even when there's only 1 device operating or I feel like messing with other channels besides 1/6/11 despite Roku's own recommendation, this subject may be closed.

I was really hoping for a software solution to keep Roku in its original location but even though the new location requires an extension cord and awkward placement of my HDMI cable, the streaming has never been smoother.

Thankfully the new location is not a "bad" location so I think we'll be able to make it work this way. Seeing the (alleged) difference between 4 and 35 MBs just by moving to a new spot really makes me want to buy a wired version knowing how much of a difference it would make to go from 35 to 200-300 with newer hardware and direct connection!

Thanks so much for your assistance @ArcherC8.

@Interdimensiona 

A few thoughts.

• The 2.4 GHz is best for distance and the 5 GHz is better for speed.
• Since the device is fixed to 2.4, I would use different SSIDs as that will allow you to control better what devices are on what band. The router may be trying to put to much on the 2.4 band or something that is high usage.
• Speaking of high usage, things like cloud backups and such can use a lot of band width which can affect other devices. 
• The best WIFI channel will differ based on many factors such as what other users in the area are using and what other type of devices that may be interfering. I prefer to use "auto" unless I need to use a specific channel.
• 2.4 tends to have the most interference.
• 1, 6, and 11 channels are non overlapping which causes others to use them also so they may be overcrowded. I have an Apple computer so I can see what WIFI channels in the area others are using.
• I would not use QoS unless it is needed. You could try it as it may help.
• Wired would be best but like a lot of things, if it works, why change it.
• Also backup the router while it is working good so as you make changes, you can always return to a specific spot or recover after a factory reset.

Thanks again for all the feedback and ideas ArcherC8.

I ended up just buying a wired roku model. Interestingly, even though my wired connection delivers up to 200-400 MBs to the attached computer(s), the latest wired Roku (the 2020 Ultra model) is reporting 88 MBs.

Not a big deal considering how 88 is more than enough for now and even more clearly not a problem with the tp-link router.

I got similar bandwidth through the 5 GHz network on the new Roku so I should be all set for now!

I went ahead and split the network names which is working for me for now.

Glad to know QoS isn't something to spring into necessarily.

Sorry we couldn't prevent the felt need of getting a new Roku but the experience in the new model has been pretty good so far!

Solution: Wired or 5GHz it is with (my new) Roku + my (generally, all-around much faster) TP Link router.